use std::collections::{BTreeMap, HashMap};
use std::path::PathBuf;

use oxc::syntax::{identifier::is_identifier_name, keyword::is_reserved_keyword};
use url::Url;

use crate::config::{self, Error, Span, Value, ValueKind, invalid, object};
use crate::import_map::ImportMap;

#[derive(Debug)]
pub struct Export {
    pub target: Url,
    pub span: Span,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Source {
    /// A local package directory.
    Local(PathBuf),
    /// A whole `jsr:` package, optionally with a version requirement.
    Jsr(crate::registry::JsrRequest),
    /// A whole `npm:` package, optionally with a version requirement.
    Npm(crate::registry::npm::NpmRequest),
    Http(Url),
}

#[derive(Debug)]
pub struct Dependency {
    pub source: Source,
    /// The binding, unless it is the name a local dependency declares for itself.
    pub name: Option<String>,
    /// Where the binding name is chosen.
    pub span: Span,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TaskDependency {
    pub name: String,
    pub span: Span,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TaskPattern {
    pub pattern: String,
    pub span: Span,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TaskEnvFile {
    pub path: String,
    pub span: Span,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TaskCommand {
    /// Run through the platform shell (`sh -c` / `cmd /C`).
    Shell(String),
    /// Spawn directly, without a shell.
    Argv(Vec<String>),
}

impl TaskCommand {
    /// A one-line rendering for task listings.
    pub fn display(&self) -> String {
        match self {
            TaskCommand::Shell(command) => command.clone(),
            TaskCommand::Argv(argv) => argv.join(" "),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Task {
    pub command: Option<TaskCommand>,
    pub description: Option<String>,
    pub dependencies: Vec<TaskDependency>,
    /// Run `dependencies` all at once instead of sequentially.
    pub parallel: bool,
    /// A dotenv file applied to this task and, recursively, its dependencies.
    pub env_file: Option<TaskEnvFile>,
    /// Declaring `files` opts the task into result caching.
    pub files: Option<Vec<TaskPattern>>,
    pub output: Vec<TaskPattern>,
    /// Environment variable names whose values join the cache key.
    pub env: Vec<String>,
    pub span: Span,
}

#[derive(Debug, Default)]
pub struct TypeConfig {
    pub imports: ImportMap,
    pub globals: Vec<String>,
}

#[derive(Debug)]
pub struct PackageConfig {
    pub name: Option<String>,
    pub version: Option<String>,
    pub description: Option<String>,
    pub exports: BTreeMap<String, Export>,
    pub dependencies: Vec<Dependency>,
    pub tasks: BTreeMap<String, Task>,
    pub import_map: ImportMap,
    pub types: TypeConfig,
    /// Each registry dependency's binding mapped to its package and that
    /// package's exports: `jsr:` and `npm:` alike.
    pub registry_map: ImportMap,
    /// Package-wide defaults for the supported JSX `compilerOptions`.
    pub compiler_options: serde_json::Map<String, serde_json::Value>,
    name_span: Option<Span>,
}

impl PackageConfig {
    pub fn parse(source: &str, base: &Url) -> Result<Self, Error> {
        Self::from_value(&config::parse(source)?, base)
    }

    pub(crate) fn from_value(root: &Value, base: &Url) -> Result<Self, Error> {
        if !matches!(base.scheme(), "file" | "http" | "https") {
            return Err(invalid(
                root.span.clone(),
                "Package configs require a file or HTTP(S) URL",
            ));
        }
        let directory = base
            .join("./")
            .map_err(|error| invalid(root.span.clone(), error.to_string()))?;
        let mut package = Self {
            name: None,
            version: None,
            description: None,
            exports: BTreeMap::new(),
            dependencies: Vec::new(),
            tasks: BTreeMap::new(),
            import_map: ImportMap::default(),
            types: TypeConfig::default(),
            registry_map: ImportMap::default(),
            compiler_options: serde_json::Map::new(),
            name_span: None,
        };
        let mut imports = None;
        let mut scopes = None;
        let mut type_config = None;
        for member in object(root)? {
            match member.key.as_str() {
                "name" => {
                    let name = string(&member.value)?;
                    if !valid_name(name) {
                        return Err(invalid(
                            member.value.span.clone(),
                            "Expected a bare package name, optionally scoped",
                        ));
                    }
                    package.name = Some(name.to_owned());
                    package.name_span = Some(member.value.span.clone());
                }
                "version" => {
                    let version = string(&member.value)?;
                    deno_semver::Version::parse_standard(version).map_err(|error| {
                        invalid(
                            member.value.span.clone(),
                            format!("Invalid package version: {error}"),
                        )
                    })?;
                    package.version = Some(version.to_owned());
                }
                "description" => package.description = Some(string(&member.value)?.to_owned()),
                "exports" => {
                    let entries: Vec<_> = match &member.value.kind {
                        ValueKind::String(_) => {
                            vec![(".", &member.value, member.value.span.clone())]
                        }
                        _ => object(&member.value)?
                            .iter()
                            .map(|entry| (entry.key.as_str(), &entry.value, entry.key_span.clone()))
                            .collect(),
                    };
                    for (key, value, span) in entries {
                        if key != "."
                            && (!key.starts_with("./")
                                || key[2..]
                                    .split('/')
                                    .any(|part| part.is_empty() || matches!(part, "." | ".."))
                                || key.contains(['*', '?', '#', '\\'])
                                || key.chars().any(char::is_control))
                        {
                            return Err(invalid(
                                span,
                                "Exports must use '.' or exact './subpath' keys",
                            ));
                        }
                        let target = string(value)?;
                        if !target.starts_with("./") {
                            return Err(invalid(
                                value.span.clone(),
                                "Export targets must be package-relative files starting with './'",
                            ));
                        }
                        let url = package_url(target, base, &value.span)?;
                        if !url.as_str().starts_with(directory.as_str())
                            || url == directory
                            || url.path().ends_with('/')
                        {
                            return Err(invalid(
                                value.span.clone(),
                                "Export target must be a file inside its package",
                            ));
                        }
                        package.exports.insert(
                            key.to_owned(),
                            Export {
                                target: url,
                                span: value.span.clone(),
                            },
                        );
                    }
                }
                "imports" => imports = Some(&member.value),
                "scopes" => scopes = Some(&member.value),
                "types" => type_config = Some(&member.value),
                "compilerOptions" => {
                    for option in object(&member.value)? {
                        // Every key is retained now: non-JSX values steer type
                        // checking, so an unconvertible value errors at its own span.
                        let value = option.value.to_value()?;
                        check_jsx_option(&option.key, &value)
                            .map_err(|message| invalid(option.value.span.clone(), message))?;
                        package.compiler_options.insert(option.key.clone(), value);
                    }
                }
                "deps" => {
                    let ValueKind::Array(entries) = &member.value.kind else {
                        return Err(invalid(member.value.span.clone(), "Expected an array"));
                    };
                    for entry in entries {
                        package.dependencies.push(dependency(entry, base)?);
                    }
                }
                "tasks" => {
                    for entry in object(&member.value)? {
                        if !valid_task_name(&entry.key) {
                            return Err(invalid(
                                entry.key_span.clone(),
                                "Task names must be non-empty and use only letters, digits, '-', '_', '.', or ':'",
                            ));
                        }
                        package.tasks.insert(entry.key.clone(), task(&entry.value)?);
                    }
                }
                _ => {}
            }
        }
        package.import_map = ImportMap::from_fields(imports, scopes, base)?;
        if let Some(type_config) = type_config {
            package.types = parse_type_config(type_config, base)?;
        }
        if let Some((name, span)) = package.name.as_ref().zip(package.name_span.as_ref())
            && let Some(key) = package.import_map.namespace_conflict(name)
        {
            return Err(invalid(
                span.clone(),
                format!("Package name {name:?} conflicts with import key {key:?}"),
            ));
        }
        let mut bindings = HashMap::new();
        for dependency in &package.dependencies {
            if let Some(name) = &dependency.name {
                package.check_binding(name, &dependency.span, &mut bindings)?;
            }
        }
        let packages: Vec<(String, String)> = package
            .dependencies
            .iter()
            .filter_map(|dependency| match (&dependency.name, &dependency.source) {
                (Some(name), Source::Jsr(request)) => {
                    Some((name.clone(), request.specifier.clone()))
                }
                (Some(name), Source::Npm(request)) => Some((name.clone(), request.request_key())),
                _ => None,
            })
            .collect();
        package.registry_map = ImportMap::packages(packages);
        Ok(package)
    }

    /// Binds each dependency, asking `declared` for the declared name of any local
    /// dependency listed by path alone. Errors are reported against this config.
    pub async fn bindings<F>(
        &self,
        mut declared: impl FnMut(Source) -> F,
    ) -> Result<BTreeMap<String, Source>, Error>
    where
        F: std::future::Future<Output = Result<Option<String>, String>>,
    {
        let mut spans = HashMap::new();
        let mut declarers = HashMap::new();
        let mut bindings = BTreeMap::new();
        for dependency in &self.dependencies {
            let (name, declarer) = match (&dependency.name, &dependency.source) {
                (Some(name), _) => (name.clone(), None),
                (None, Source::Jsr(_)) => unreachable!("jsr: dependencies are named when parsed"),
                (None, Source::Npm(_)) => unreachable!("npm: dependencies are named when parsed"),
                (None, source) => {
                    let config = match source {
                        Source::Local(directory) => {
                            directory.join("avril.conf").display().to_string()
                        }
                        Source::Http(directory) => {
                            directory.join("avril.conf").unwrap().to_string()
                        }
                        Source::Jsr(_) => unreachable!(),
                        Source::Npm(_) => unreachable!(),
                    };
                    let name = declared(source.clone())
                        .await
                        .map_err(|error| {
                            invalid(
                                dependency.span.clone(),
                                format!(
                                    "Cannot read the name of dependency {}: {error}",
                                    config
                                ),
                            )
                        })?
                        .ok_or_else(|| {
                            invalid(
                                dependency.span.clone(),
                                format!(
                                    "Dependency {} declares no name; give this entry {{from, name}}",
                                    config
                                ),
                            )
                        })?;
                    (name, Some(config))
                }
            };
            self.check_binding(&name, &dependency.span, &mut spans)
                .map_err(|mut error| {
                    // A duplicate of an earlier inferred name needs that dependency's context.
                    if let Some(config) = declarer.as_ref().or_else(|| declarers.get(&name)) {
                        error.message = format!(
                            "{}; the dependency's name comes from {}",
                            error.message, config
                        );
                    }
                    error
                })?;
            if let Some(config) = declarer {
                declarers.insert(name.clone(), config);
            }
            bindings.insert(name, dependency.source.clone());
        }
        Ok(bindings)
    }

    fn check_binding(
        &self,
        name: &str,
        span: &Span,
        bindings: &mut HashMap<String, Span>,
    ) -> Result<(), Error> {
        if self.name.as_deref() == Some(name) {
            return Err(Error {
                kind: crate::config::ErrorKind::Syntax,
                message: format!(
                    "Dependency binding {name:?} conflicts with the package's self name"
                ),
                span: span.clone(),
                previous: self.name_span.clone(),
            });
        }
        if let Some(previous) = bindings.get(name) {
            return Err(Error {
                kind: crate::config::ErrorKind::Syntax,
                message: format!("Duplicate dependency binding {name:?}"),
                span: span.clone(),
                previous: Some(previous.clone()),
            });
        }
        if let Some(key) = self.import_map.namespace_conflict(name) {
            return Err(invalid(
                span.clone(),
                format!("Dependency binding {name:?} conflicts with import key {key:?}"),
            ));
        }
        bindings.insert(name.to_owned(), span.clone());
        Ok(())
    }
}

fn valid_task_name(name: &str) -> bool {
    !name.is_empty()
        && name
            .bytes()
            .all(|ch| ch.is_ascii_alphanumeric() || matches!(ch, b'-' | b'_' | b'.' | b':'))
}

fn task(value: &Value) -> Result<Task, Error> {
    let span = value.span.clone();
    let command = |value: &Value| -> Result<TaskCommand, Error> {
        match &value.kind {
            ValueKind::Array(entries) => {
                if entries.is_empty() {
                    return Err(invalid(
                        value.span.clone(),
                        "Task command arrays cannot be empty",
                    ));
                }
                let mut argv = Vec::new();
                for entry in entries {
                    argv.push(string(entry)?.to_owned());
                }
                if argv[0].is_empty() {
                    return Err(invalid(
                        entries[0].span.clone(),
                        "The first element of a task command array cannot be empty",
                    ));
                }
                Ok(TaskCommand::Argv(argv))
            }
            _ => {
                let command = string(value).map_err(|_| {
                    invalid(
                        value.span.clone(),
                        "Expected a string (shell command) or an array of strings (argv) for 'command'",
                    )
                })?;
                if command.trim().is_empty() {
                    return Err(invalid(value.span.clone(), "Task commands cannot be empty"));
                }
                Ok(TaskCommand::Shell(command.to_owned()))
            }
        }
    };
    match &value.kind {
        ValueKind::String(_) => Ok(Task {
            command: Some(command(value)?),
            description: None,
            dependencies: Vec::new(),
            parallel: false,
            env_file: None,
            files: None,
            output: Vec::new(),
            env: Vec::new(),
            span,
        }),
        ValueKind::Object(fields) => {
            let mut task = Task {
                command: None,
                description: None,
                dependencies: Vec::new(),
                parallel: false,
                env_file: None,
                files: None,
                output: Vec::new(),
                env: Vec::new(),
                span: span.clone(),
            };
            let mut dependency_spans: HashMap<String, Span> = HashMap::new();
            let mut parallel_span = None;
            for field in fields {
                match field.key.as_str() {
                    "command" => task.command = Some(command(&field.value)?),
                    "description" => task.description = Some(string(&field.value)?.to_owned()),
                    "dependencies" => {
                        let ValueKind::Array(entries) = &field.value.kind else {
                            return Err(invalid(
                                field.value.span.clone(),
                                "Expected an array of task names",
                            ));
                        };
                        for entry in entries {
                            let name = string(entry)?;
                            if !valid_task_name(name) {
                                return Err(invalid(entry.span.clone(), "Expected a task name"));
                            }
                            if let Some(previous) = dependency_spans.get(name) {
                                return Err(Error {
                                    kind: crate::config::ErrorKind::Syntax,
                                    message: format!("Duplicate task dependency {name:?}"),
                                    span: entry.span.clone(),
                                    previous: Some(previous.clone()),
                                });
                            }
                            dependency_spans.insert(name.to_owned(), entry.span.clone());
                            task.dependencies.push(TaskDependency {
                                name: name.to_owned(),
                                span: entry.span.clone(),
                            });
                        }
                    }
                    "parallel" => {
                        let ValueKind::Bool(parallel) = field.value.kind else {
                            return Err(invalid(field.value.span.clone(), "Expected a boolean"));
                        };
                        task.parallel = parallel;
                        parallel_span = Some(field.value.span.clone());
                    }
                    "envFile" => {
                        let path = string(&field.value)?;
                        if path.trim().is_empty() {
                            return Err(invalid(
                                field.value.span.clone(),
                                "Task env file paths cannot be empty",
                            ));
                        }
                        task.env_file = Some(TaskEnvFile {
                            path: path.to_owned(),
                            span: field.value.span.clone(),
                        });
                    }
                    "files" | "output" => {
                        let ValueKind::Array(entries) = &field.value.kind else {
                            return Err(invalid(
                                field.value.span.clone(),
                                "Expected an array of glob patterns",
                            ));
                        };
                        let mut patterns = Vec::new();
                        for entry in entries {
                            let pattern = string(entry)?;
                            avril_task::validate_pattern(pattern)
                                .map_err(|error| invalid(entry.span.clone(), error.to_string()))?;
                            if field.key == "output" {
                                avril_task::validate_output_pattern(pattern).map_err(|error| {
                                    invalid(entry.span.clone(), error.to_string())
                                })?;
                            }
                            patterns.push(TaskPattern {
                                pattern: pattern.to_owned(),
                                span: entry.span.clone(),
                            });
                        }
                        if field.key == "files" {
                            task.files = Some(patterns);
                        } else {
                            task.output = patterns;
                        }
                    }
                    "env" => {
                        let ValueKind::Array(entries) = &field.value.kind else {
                            return Err(invalid(
                                field.value.span.clone(),
                                "Expected an array of environment variable names",
                            ));
                        };
                        let mut seen: HashMap<String, Span> = HashMap::new();
                        for entry in entries {
                            let name = string(entry)?;
                            if !valid_env_name(name) {
                                return Err(invalid(
                                    entry.span.clone(),
                                    "Expected an environment variable name",
                                ));
                            }
                            if let Some(previous) = seen.get(name) {
                                return Err(Error {
                                    kind: crate::config::ErrorKind::Syntax,
                                    message: format!("Duplicate task env name {name:?}"),
                                    span: entry.span.clone(),
                                    previous: Some(previous.clone()),
                                });
                            }
                            seen.insert(name.to_owned(), entry.span.clone());
                            task.env.push(name.to_owned());
                        }
                    }
                    _ => {}
                }
            }
            if task.parallel && task.dependencies.is_empty() {
                return Err(invalid(
                    parallel_span.unwrap(),
                    "Task 'parallel' requires 'dependencies'",
                ));
            }
            if task.files.is_none() && (!task.output.is_empty() || !task.env.is_empty()) {
                return Err(invalid(
                    span.clone(),
                    "Task 'output' and 'env' require 'files': declaring 'files' enables result caching",
                ));
            }
            if task.command.is_none() && task.dependencies.is_empty() {
                return Err(invalid(
                    span,
                    "Tasks must define a 'command' or 'dependencies'",
                ));
            }
            Ok(task)
        }
        _ => Err(invalid(
            span,
            "Expected a task command string or an object with 'command', 'description', 'dependencies', 'parallel', 'envFile', 'files', 'output', or 'env'",
        )),
    }
}

fn valid_env_name(name: &str) -> bool {
    let mut bytes = name.bytes();
    bytes
        .next()
        .is_some_and(|ch| ch.is_ascii_alphabetic() || ch == b'_')
        && bytes.all(|ch| ch.is_ascii_alphanumeric() || ch == b'_')
}

fn dependency(entry: &Value, base: &Url) -> Result<Dependency, Error> {
    let (from, name) = match &entry.kind {
        ValueKind::String(_) => (entry, None),
        ValueKind::Object(_) => {
            let mut from = None;
            let mut name = None;
            for field in object(entry)? {
                match field.key.as_str() {
                    "from" => from = Some(&field.value),
                    "name" => name = Some(&field.value),
                    _ => {}
                }
            }
            let (Some(from), Some(name)) = (from, name) else {
                return Err(invalid(
                    entry.span.clone(),
                    "Dependency objects require both 'from' and 'name'; a string uses the dependency's own name",
                ));
            };
            (from, Some(name))
        }
        _ => {
            return Err(invalid(
                entry.span.clone(),
                "Expected a dependency path, HTTP(S) directory URL, jsr: package, or {from, name}",
            ));
        }
    };
    let binding = match name {
        Some(name) => {
            let binding = string(name)?;
            if !valid_name(binding) {
                return Err(invalid(
                    name.span.clone(),
                    "Expected a dependency binding name, optionally scoped",
                ));
            }
            Some(binding.to_owned())
        }
        None => None,
    };
    let target = string(from)?;
    let (source, implicit) = if target.starts_with("jsr:") {
        let span = &from.span;
        let request = crate::registry::parse_jsr_request(target)
            .map_err(|error| invalid(span.clone(), error.to_string()))?;
        if request.version_req.tag().is_some() {
            return Err(invalid(
                span.clone(),
                "JSR version tags are not supported; use a semver range",
            ));
        }
        if request.subpath.is_some() || target.ends_with('/') {
            return Err(invalid(
                span.clone(),
                "Dependencies are whole packages; map a subpath in imports instead",
            ));
        }
        crate::registry::validate_name(&request.name)
            .map_err(|error| invalid(span.clone(), error.to_string()))?;
        let name = request.name.clone();
        (Source::Jsr(request), Some(name))
    } else if target.starts_with("npm:") {
        let span = &from.span;
        let request = crate::registry::npm::parse_npm_request(target)
            .map_err(|error| invalid(span.clone(), error.to_string()))?;
        if request.subpath.is_some() || target.ends_with('/') {
            return Err(invalid(
                span.clone(),
                "Dependencies are whole packages; map a subpath in imports instead",
            ));
        }
        let name = request.name.clone();
        (Source::Npm(request), Some(name))
    } else if Url::parse(target).is_ok_and(|url| matches!(url.scheme(), "http" | "https"))
        || (matches!(base.scheme(), "http" | "https")
            && (target.starts_with("./") || target.starts_with("../")))
    {
        let url = package_url(target, base, &from.span)?;
        if !matches!(url.scheme(), "http" | "https")
            || !url.username().is_empty()
            || url.password().is_some()
            || !target.ends_with('/')
        {
            return Err(invalid(
                from.span.clone(),
                "HTTP(S) dependencies must be credential-free directory URLs ending with '/'",
            ));
        }
        (Source::Http(url), None)
    } else if target.starts_with("./") || target.starts_with("../") {
        let path = package_url(target, base, &from.span)?
            .to_file_path()
            .map_err(|_| invalid(from.span.clone(), "Expected a local package path"))?;
        (Source::Local(path), None)
    } else {
        return Err(invalid(
            from.span.clone(),
            "Dependencies must be jsr: packages, HTTP(S) directory URLs, or config-relative paths starting with './' or '../'",
        ));
    };
    Ok(Dependency {
        source,
        name: binding.or(implicit),
        span: name.unwrap_or(from).span.clone(),
    })
}

/// Whether `name` is a bare package name, optionally scoped.
pub fn valid_name(name: &str) -> bool {
    let valid_part = |part: &str| {
        !part.is_empty()
            && !part.starts_with('.')
            && part
                .bytes()
                .all(|ch| ch.is_ascii_alphanumeric() || matches!(ch, b'-' | b'_' | b'.'))
    };
    match name.strip_prefix('@') {
        Some(scoped) => scoped
            .split_once('/')
            .is_some_and(|(scope, name)| valid_part(scope) && valid_part(name)),
        None => valid_part(name),
    }
}

/// The `compilerOptions` validated for the runtime; every key is retained
/// for type checking, in `avril.conf` and `tsconfig.json` alike.
pub const JSX_OPTIONS: [&str; 4] = ["jsx", "jsxImportSource", "jsxFactory", "jsxFragmentFactory"];

pub fn check_jsx_option(key: &str, value: &serde_json::Value) -> Result<(), String> {
    if !JSX_OPTIONS.contains(&key) {
        return Ok(());
    }
    let text = value
        .as_str()
        .filter(|text| !text.trim().is_empty())
        .ok_or_else(|| format!("compilerOptions.{key} must be a nonempty string"))?;
    if key == "jsx"
        && !matches!(
            text,
            "react" | "react-jsx" | "react-jsxdev" | "preserve" | "react-native"
        )
    {
        return Err("Unsupported compilerOptions.jsx".into());
    }
    if matches!(key, "jsxFactory" | "jsxFragmentFactory") {
        let mut parts = text.split('.');
        let root = parts.next().unwrap();
        let valid = match root {
            "this" => true,
            "import" => parts.next() == Some("meta"),
            _ => is_identifier_name(root) && !is_reserved_keyword(root),
        };
        if !valid || !parts.all(is_identifier_name) {
            return Err(format!(
                "compilerOptions.{key} must be an identifier or dotted member expression"
            ));
        }
    }
    Ok(())
}

fn parse_type_config(value: &Value, base: &Url) -> Result<TypeConfig, Error> {
    let members = object(value)?;
    let mut imports = None;
    let mut globals = Vec::new();
    for member in members {
        match member.key.as_str() {
            "imports" => imports = Some(&member.value),
            "globals" => {
                let ValueKind::Array(entries) = &member.value.kind else {
                    return Err(invalid(member.value.span.clone(), "Expected an array"));
                };
                for entry in entries {
                    let target = string(entry)?;
                    let url = if target.starts_with("./")
                        || target.starts_with("../")
                        || target.starts_with('/')
                    {
                        base.join(target)
                            .map_err(|error| invalid(entry.span.clone(), error.to_string()))?
                    } else {
                        Url::parse(target).map_err(|_| {
                            invalid(
                                entry.span.clone(),
                                "Global type entries must be URLs or relative paths",
                            )
                        })?
                    };
                    globals.push(url.to_string());
                }
            }
            _ => {}
        }
    }
    Ok(TypeConfig {
        imports: ImportMap::from_fields(imports, None, base)?,
        globals,
    })
}

fn string(value: &Value) -> Result<&str, Error> {
    match &value.kind {
        ValueKind::String(value) => Ok(value),
        _ => Err(invalid(value.span.clone(), "Expected a string")),
    }
}

fn package_url(target: &str, base: &Url, span: &Span) -> Result<Url, Error> {
    let lower = target.to_ascii_lowercase();
    if target.contains('\\')
        || target.chars().any(char::is_control)
        || lower.contains("%2f")
        || lower.contains("%5c")
    {
        return Err(invalid(span.clone(), "Invalid package path"));
    }
    let url = base
        .join(target)
        .map_err(|error| invalid(span.clone(), error.to_string()))?;
    if url.query().is_some() || url.fragment().is_some() {
        return Err(invalid(
            span.clone(),
            "Package paths cannot contain queries or fragments",
        ));
    }
    let decoded = percent_encoding::percent_decode_str(url.path())
        .decode_utf8()
        .map_err(|_| invalid(span.clone(), "Package paths must be valid UTF-8"))?;
    if decoded.contains('\0') {
        return Err(invalid(
            span.clone(),
            "Package paths must be without NUL bytes",
        ));
    }
    Ok(url)
}

#[cfg(test)]
mod tests {
    use super::PackageConfig;
    use url::Url;

    const BASE: &str = "https://example.test/project/avril.conf";

    #[test]
    fn type_config_normalizes_global_modules_and_keeps_imports_separate() {
        let config = PackageConfig::parse(
            r#"{
                imports: { "npm:legacy-sdk": "npm:runtime-sdk" },
                types: {
                    imports: { "npm:legacy-sdk": "npm:@types/legacy-sdk@^3", "https://example.test/project/src/old": "./types/legacy.d.ts", "legacy/": null },
                    globals: ["./types/globals.d.ts", "npm:@types/node@^22", "https://types.test/global.d.ts"]
                }
            }"#,
            &Url::parse(BASE).unwrap(),
        )
        .unwrap();
        assert_eq!(
            config.types.globals,
            [
                "https://example.test/project/types/globals.d.ts",
                "npm:@types/node@^22",
                "https://types.test/global.d.ts",
            ]
        );
        let referrer = Url::parse("https://example.test/project/src/module.ts").unwrap();
        assert_eq!(
            config
                .types
                .imports
                .resolve("npm:legacy-sdk", &referrer)
                .unwrap(),
            Some("npm:@types/legacy-sdk@^3".into())
        );
        assert_eq!(
            config
                .import_map
                .resolve("npm:legacy-sdk", &referrer)
                .unwrap(),
            Some("npm:runtime-sdk".into())
        );
        assert_eq!(
            config.types.imports.resolve("./old", &referrer).unwrap(),
            Some("https://example.test/project/types/legacy.d.ts".into())
        );
        assert!(
            config
                .types
                .imports
                .resolve("legacy/subpath", &referrer)
                .is_err()
        );
    }

    #[test]
    fn type_config_defaults_empty_and_rejects_malformed_shapes() {
        let base = Url::parse(BASE).unwrap();
        let config = PackageConfig::parse("{}", &base).unwrap();
        assert!(config.types.globals.is_empty());
        assert!(
            config
                .types
                .imports
                .resolve("anything", &base)
                .unwrap()
                .is_none()
        );
        for source in [
            r#"{ types: [] }"#,
            r#"{ types: { imports: [] } }"#,
            r#"{ types: { globals: "./global.d.ts" } }"#,
            r#"{ types: { globals: ["bare-module"] } }"#,
            r#"{ types: { globals: [42] } }"#,
        ] {
            assert!(PackageConfig::parse(source, &base).is_err(), "{source}");
        }
    }
}