import { getMarkdownTheme } from "@earendil-works/pi-coding-agent";
import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
import { Markdown } from "@earendil-works/pi-tui";
import {
  analyzeBash,
  assessAnalysis,
  assessPath,
  type PermissionPolicy,
  type PermissionVerdict,
} from "bash-effect-analyzer";
import { hostname } from "node:os";
import * as path from "node:path";
import { compactConfirm } from "../_char_common/compact-confirm";
import { loadSettings } from "../_char_common/settings";
import { resolvesToFilesystemRoot, rootTargetCommand } from "./root-target";

interface PermissionConfig {
  allowedCommandPrefixes: string[];
  writableDirectories: string[];
  readableDirectories: string[];
  yoloDisabledHosts: string[];
}

function readPermissionConfig(cwd: string): PermissionConfig {
  const result: PermissionConfig = {
    allowedCommandPrefixes: [],
    writableDirectories: [],
    readableDirectories: [],
    yoloDisabledHosts: [],
  };
  const settings = loadSettings(cwd);
  const pg = settings.permissionGate;
  if (pg && typeof pg === "object") {
    const gate = pg as Record<string, unknown>;
    const stringList = (v: unknown): string[] =>
      Array.isArray(v) ? v.filter((s): s is string => typeof s === "string") : [];
    result.allowedCommandPrefixes.push(...stringList(gate.allowedCommandPrefixes));
    result.writableDirectories.push(...stringList(gate.writableDirectories));
    result.readableDirectories.push(...stringList(gate.readableDirectories));
    result.yoloDisabledHosts.push(...stringList(gate.yoloDisabledHosts));
  }
  return result;
}

function bullet(items: string[], prefix = "-"): string {
  return items.map((s) => `${prefix} ${s}`).join("\n");
}

function formatAllowMessage(label: string, verdict: PermissionVerdict): string {
  return `🔓 auto-approved ${label}\n${bullet(verdict.allowReasons, "  •")}`;
}

interface PromptDetail {
  heading: string;
  body: string;
}

function buildPromptMarkdown(detail: PromptDetail, verdict: PermissionVerdict): string {
  const sections = [detail.body, `**Concerns**\n${bullet(verdict.promptReasons)}`];
  if (verdict.allowReasons.length > 0) {
    sections.push(
      `**Benign effects** (would auto-approve on their own)\n${bullet(verdict.allowReasons)}`,
    );
  }
  return sections.join("\n\n");
}

// Render the verdict details as a Markdown widget pinned above the editor,
// then ask via the compact single-line prompt. The built-in `ctx.ui.confirm`
// draws ~11 rows of chrome (borders, spacers, key hints) for what is
// fundamentally a y/n question, and embedding the long body into its title
// also triggers a redraw loop when the rendered prompt exceeds the terminal
// height. `compactConfirm` keeps the dialog itself to a single wrapped line
// and requires the user to type "yes" or "no" explicitly so a stray
// keystroke can't approve a destructive operation.
async function promptForApproval(
  ctx: ExtensionContext,
  detail: PromptDetail,
  verdict: PermissionVerdict,
): Promise<boolean> {
  const markdown = buildPromptMarkdown(detail, verdict);
  ctx.ui.setWidget(
    "permission-gate-prompt",
    (_tui, _theme) => new Markdown(markdown, 1, 0, getMarkdownTheme()),
  );
  try {
    return await compactConfirm(ctx, detail.heading, "");
  } finally {
    ctx.ui.setWidget("permission-gate-prompt", undefined);
  }
}

export default function (pi: ExtensionAPI) {
  let yolo = false;
  let yoloDisabled = false;
  let strict = false;
  let strictReads = false;
  let allowedCommands: string[] = [];
  let configWritableDirs: string[] = [];
  let configReadableDirs: string[] = [];
  let lastPersistedSnapshot: string | null = null;

  function persistAllowedCommands() {
    const snapshot = JSON.stringify(allowedCommands);
    if (snapshot === lastPersistedSnapshot) return;
    pi.appendEntry("permission-gate-allowed", { commands: [...allowedCommands] });
    lastPersistedSnapshot = snapshot;
  }

  const DIM = "\x1b[2m";
  const RESET = "\x1b[22m";

  function buildPolicy(cwd: string): PermissionPolicy {
    return {
      cwd,
      allowedPrefixes: allowedCommands,
      // /dev/null is the universal Unix bit-bucket; redirecting to it has no
      // filesystem effect, so it's always safe regardless of cwd.
      writablePaths: ["/dev/null", ...configWritableDirs],
      restrictReads: strictReads,
      readablePaths: configReadableDirs,
    };
  }

  function updateStatus(ctx: {
    ui: { setStatus(id: string, text: string | undefined): void };
  }) {
    if (yolo) {
      ctx.ui.setStatus("permission-gate", `${DIM}🔓 yolo${RESET}`);
    } else if (strict && strictReads) {
      ctx.ui.setStatus("permission-gate", `${DIM}🔒 strict + strict-reads${RESET}`);
    } else if (strict) {
      ctx.ui.setStatus("permission-gate", `${DIM}🔒 strict${RESET}`);
    } else if (strictReads) {
      ctx.ui.setStatus("permission-gate", `${DIM}🔒 strict-reads${RESET}`);
    } else if (allowedCommands.length > 0) {
      ctx.ui.setStatus(
        "permission-gate",
        `${DIM}🔓 ${allowedCommands.length} allowed command(s)${RESET}`,
      );
    } else {
      ctx.ui.setStatus("permission-gate", undefined);
    }
  }

  pi.on("session_start", async (_event, ctx) => {
    const config = readPermissionConfig(ctx.cwd);
    allowedCommands = [...config.allowedCommandPrefixes];
    configWritableDirs = config.writableDirectories.map((d) => path.resolve(ctx.cwd, d));
    configReadableDirs = config.readableDirectories.map((d) => path.resolve(ctx.cwd, d));
    yoloDisabled = config.yoloDisabledHosts.includes(hostname());
    // Each turn_start writes a full snapshot, so only the most recent one
    // reflects the session's actual state - unioning all historical snapshots
    // would resurrect any command the user ever toggled off.
    let lastSnapshot: string[] | null = null;
    for (const entry of ctx.sessionManager.getEntries()) {
      if (entry.type === "custom" && entry.customType === "permission-gate-allowed") {
        lastSnapshot = (entry.data as { commands?: string[] })?.commands ?? [];
      }
    }
    if (lastSnapshot) {
      for (const p of lastSnapshot) {
        if (!allowedCommands.includes(p)) allowedCommands.push(p);
      }
      // Seed the dedup key so we don't immediately re-append an identical
      // snapshot on the next turn_start.
      lastPersistedSnapshot = JSON.stringify(allowedCommands);
    }
    updateStatus(ctx);
  });

  pi.on("turn_start", async () => {
    if (allowedCommands.length > 0) persistAllowedCommands();
  });

  // prettier-ignore
  const PERM_MODES = {
    yolo: {
      on: "🔓 yolo mode on - all permission gates disabled",
      off: "🔒 yolo mode off - permission gates active",
      toggle: () => { yolo = !yolo; if (yolo) { strict = false; strictReads = false; } return yolo; },
    },
    strict: {
      on: "🔒 strict mode on - any action requiring approval will be auto-denied",
      off: "🔓 strict mode off - approval prompts re-enabled",
      toggle: () => { strict = !strict; if (strict) yolo = false; return strict; },
    },
    "strict-reads": {
      on: "🔒 strict-reads mode on - reads confined to cwd + readableDirectories (bash commands and read/ls/grep/find tools)",
      off: "🔓 strict-reads mode off",
      toggle: () => { strictReads = !strictReads; if (strictReads) yolo = false; return strictReads; },
    },
  } as const satisfies Record<string, { on: string; off: string; toggle: () => boolean }>;
  type PermMode = keyof typeof PERM_MODES;

  function describeState(): string {
    const flags = [
      yolo ? "yolo" : null,
      strict ? "strict" : null,
      strictReads ? "strict-reads" : null,
    ].filter((f): f is string => f !== null);
    const modeLine =
      flags.length === 0
        ? "all modes off (interactive prompting)"
        : `active: ${flags.join(", ")}`;
    const allowLine =
      allowedCommands.length === 0
        ? "no allowed command prefixes"
        : `allowed prefixes:\n${allowedCommands.map((c) => `  • ${c}`).join("\n")}`;
    return `${modeLine}\n${allowLine}`;
  }

  pi.registerCommand("perms", {
    description: "Show or toggle permission-gate modes: /perms [yolo|strict|strict-reads]",
    getArgumentCompletions: (prefix: string) => {
      const items = (Object.keys(PERM_MODES) as PermMode[])
        .filter((m) => m.startsWith(prefix))
        .map((m) => ({ value: m, label: m }));
      return items.length > 0 ? items : null;
    },
    handler: async (args, ctx) => {
      const arg = args?.trim();
      if (!arg) {
        ctx.ui.notify(describeState(), "info");
        return;
      }
      if (arg === "yolo" && !yolo && yoloDisabled) {
        ctx.ui.notify("yolo mode is disabled on this host (permissionGate.yoloDisabledHosts)", "warning");
        return;
      }
      if (!(arg in PERM_MODES)) {
        ctx.ui.notify(
          `Unknown mode "${arg}". Valid: ${Object.keys(PERM_MODES).join(", ")}`,
          "warning",
        );
        return;
      }
      const mode = PERM_MODES[arg as PermMode];
      const enabled = mode.toggle();
      ctx.ui.notify(enabled ? mode.on : mode.off, "info");
      updateStatus(ctx);
    },
  });

  pi.registerCommand("allow", {
    description:
      "Toggle a command prefix on the session allow-list - ALL effects of matching commands are auto-approved",
    getArgumentCompletions: (prefix: string) => {
      if (allowedCommands.length === 0) return null;
      const items = allowedCommands.map((c) => ({ value: c, label: c }));
      const filtered = items.filter((i) => i.value.startsWith(prefix));
      return filtered.length > 0 ? filtered : null;
    },
    handler: async (args, ctx) => {
      const command = args?.trim();
      if (!command) {
        if (allowedCommands.length === 0) {
          ctx.ui.notify("No allowed commands. Usage: /allow <command>", "info");
        } else {
          ctx.ui.notify(
            `Allowed commands:\n${allowedCommands.map((c) => `  • ${c}`).join("\n")}`,
            "info",
          );
        }
        return;
      }
      const existingIndex = allowedCommands.indexOf(command);
      if (existingIndex >= 0) {
        allowedCommands.splice(existingIndex, 1);
        ctx.ui.notify(`🔒 "${command}" is no longer auto-approved`, "info");
      } else {
        allowedCommands.push(command);
        ctx.ui.notify(
          `🔓 Commands matching "${command}" are now auto-approved for this session`,
          "info",
        );
      }
      persistAllowedCommands();
      updateStatus(ctx);
    },
  });

  async function enforceVerdict(opts: {
    ctx: ExtensionContext;
    verdict: PermissionVerdict;
    allowLabel: string;
    deniedLine: string;
    promptDetail: PromptDetail;
  }): Promise<{ block: true; reason: string } | undefined> {
    const { ctx, verdict, allowLabel, deniedLine, promptDetail } = opts;

    if (verdict.decision === "allow") {
      if (ctx.hasUI) {
        ctx.ui.notify(formatAllowMessage(allowLabel, verdict), "info");
      }
      return;
    }

    if (strict) {
      return {
        block: true,
        reason: `Denied by strict mode. Concerns:\n${bullet(verdict.promptReasons)}`,
      };
    }
    if (!ctx.hasUI) {
      return {
        block: true,
        reason: `Cannot prompt for permission (no UI). ${deniedLine}\n${bullet(verdict.promptReasons, "  •")}`,
      };
    }
    const ok = await promptForApproval(ctx, promptDetail, verdict);
    if (!ok) {
      return {
        block: true,
        reason: `Denied by user. Concerns:\n${bullet(verdict.promptReasons)}`,
      };
    }
    return;
  }

  pi.on("tool_call", async (event, ctx) => {
    if (event.toolName === "bash") {
      const command = (event.input as { command?: string }).command ?? "";
      const analysis = await analyzeBash(command, {
        environment: {
          HOME: process.env.HOME,
          OLDPWD: process.env.OLDPWD,
          CDPATH: process.env.CDPATH,
        },
      });
      const deniedCommand = rootTargetCommand(analysis, ctx.cwd);
      if (deniedCommand) {
        return {
          block: true,
          reason:
            deniedCommand === "find"
              ? "Denied: `find` may not search filesystem root `/` because it would take too long. Search a narrower directory instead."
              : "Denied: `rm` may not target filesystem root `/`.",
        };
      }
      if (yolo) return;

      const policy = buildPolicy(ctx.cwd);
      const verdict = assessAnalysis(analysis, policy);
      return enforceVerdict({
        ctx,
        verdict,
        allowLabel: `\`${command}\``,
        deniedLine: `Denied: ${command}`,
        promptDetail: { heading: "Bash command", body: "```bash\n" + command + "\n```" },
      });
    }

    if (event.toolName === "find") {
      const rawPath = (event.input as { path?: string }).path ?? ".";
      if (resolvesToFilesystemRoot(ctx.cwd, rawPath)) {
        return {
          block: true,
          reason:
            "Denied: `find` may not search filesystem root `/` because it would take too long. Search a narrower directory instead.",
        };
      }
    }

    if (event.toolName === "read") {
      const rawPath = (event.input as { path?: string }).path;
      if (rawPath) {
        const filename = path.basename(path.resolve(ctx.cwd, rawPath));
        if (filename === ".env" || filename === ".env.local") {
          return {
            block: true,
            reason: `Denied: \`read\` may not access \`${filename}\` because it may contain secrets.`,
          };
        }
      }
    }

    if (yolo) return;

    if (event.toolName === "edit" || event.toolName === "write") {
      return resolvePathDecision({
        ctx,
        rawPath:
          (event.input as { path?: string; file_path?: string }).path ??
          (event.input as { file_path?: string }).file_path,
        verdict: (p) => assessPath("write", p, buildPolicy(ctx.cwd)),
        confirmTitle: "Write outside CWD",
        label: `${event.toolName}`,
      });
    }

    // Read-style tools are only gated in strict-reads mode — in normal
    // operation reads are unrestricted and the bash safe-command list does the
    // policy work.
    if (
      strictReads &&
      (event.toolName === "read" ||
        event.toolName === "ls" ||
        event.toolName === "grep" ||
        event.toolName === "find")
    ) {
      const rawPath = (event.input as { path?: string }).path;
      // ls/grep/find without a path default to cwd, which is always allowed.
      if (!rawPath) return;
      return resolvePathDecision({
        ctx,
        rawPath,
        verdict: (p) => assessPath("read", p, buildPolicy(ctx.cwd)),
        confirmTitle: "Read outside CWD",
        label: `${event.toolName}`,
      });
    }
  });

  async function resolvePathDecision(opts: {
    ctx: ExtensionContext;
    rawPath: string | undefined;
    verdict: (rawPath: string) => PermissionVerdict;
    confirmTitle: string;
    label: string;
  }): Promise<{ block: true; reason: string } | undefined> {
    const { ctx, rawPath, verdict: makeVerdict, confirmTitle, label } = opts;
    if (!rawPath) return;

    const resolved = path.resolve(ctx.cwd, rawPath);
    return enforceVerdict({
      ctx,
      verdict: makeVerdict(rawPath),
      allowLabel: `${label} \`${rawPath}\``,
      deniedLine: `Denied ${label} ${rawPath}`,
      promptDetail: {
        heading: confirmTitle,
        body: `**Tool:** \`${label}\`\n\n**Path:** \`${rawPath}\`\n\n**Resolved:** \`${resolved}\``,
      },
    });
  }
}