/**
 * @fileoverview Claude Code hooks configuration generator.
 *
 * Generates `.claude/settings.local.json` with hook definitions that POST
 * to Codeman's `/api/hook-event` endpoint when Claude Code fires hooks.
 * Uses `$CODEMAN_API_URL`, `$CODEMAN_SESSION_ID`, and `$CODEMAN_HOOK_SECRET_FILE`
 * env vars (set on every managed session) so the config is static per case
 * directory and free of secret values.
 *
 * Key exports:
 * - `generateHooksConfig()` — returns hooks object for settings.local.json
 * - `writeHooksConfig(casePath)` — writes hooks + env config to disk
 * - `updateCaseEnvVars(casePath, envVars)` — merges env vars into settings
 *
 * Hook events generated: `idle_prompt`, `permission_prompt`, `elicitation_dialog`,
 * `stop`, `teammate_idle`, `task_completed`
 *
 * Hook categories: `Notification` (3 matchers), `Stop` (1), `TeammateIdle` (1),
 * `TaskCompleted` (1)
 *
 * @dependencies types (HookEventType), config/auth-config (HOOK_TIMEOUT_MS)
 * @consumedby web/server (session creation), session-cli-builder (env setup)
 *
 * @module hooks-config
 */

import { existsSync } from 'node:fs';
import { readFile, writeFile, mkdir } from 'node:fs/promises';
import { join } from 'node:path';

import type { HookEventType } from './types.js';
import { HOOK_TIMEOUT_MS } from './config/auth-config.js';

/**
 * Serializes read-modify-write access to a `settings.local.json` path. Every
 * writer in this module (hooks, env, model, statusLine) shares this map, so
 * concurrent updates to the SAME file — e.g. session-create writing hooks/model
 * while an App-Settings toggle injects the statusLine into the same repo — can't
 * lose each other's changes through interleaved read-then-write. Per-path chains
 * are independent; the map self-prunes when a path's chain goes idle.
 */
const settingsWriteLocks = new Map<string, Promise<unknown>>();
function withSettingsLock<T>(path: string, fn: () => Promise<T>): Promise<T> {
  const prev = settingsWriteLocks.get(path) ?? Promise.resolve();
  const run = prev.then(fn, fn); // run after the prior writer, regardless of its outcome
  // Tail never rejects, so a failed write doesn't poison subsequent writers.
  const tail = run.then(
    () => {},
    () => {}
  );
  settingsWriteLocks.set(path, tail);
  void tail.then(() => {
    if (settingsWriteLocks.get(path) === tail) settingsWriteLocks.delete(path);
  });
  return run;
}

/**
 * Generates the hooks section for .claude/settings.local.json
 *
 * The hook commands read stdin JSON from Claude Code (contains tool_name,
 * tool_input, etc.) and forward it as the `data` field to Codeman's API.
 * Env vars are resolved at runtime by the shell, so the config is static
 * per case directory.
 */
export function generateHooksConfig(): { hooks: Record<string, unknown[]> } {
  // Read Claude Code's stdin JSON and forward it as the data field.
  // Falls back to empty object if stdin is unavailable or malformed.
  // COD-54: present the per-instance hook secret so the bypass keeps working while
  // a tunnel is running. The value is read from the secret file AT EXECUTION TIME
  // (path via $CODEMAN_HOOK_SECRET_FILE, set in every managed session's env), so it
  // never lands in this config and rotation needs no respawn. If the var/file is
  // missing the header is empty — the middleware then allows the request only on
  // the plain loopback bypass (tunnel down), same as pre-secret behavior.
  const curlCmd = (event: HookEventType) =>
    `HOOK_DATA=$(cat 2>/dev/null || echo '{}'); ` +
    `printf '{"event":"${event}","sessionId":"%s","data":%s}' "$CODEMAN_SESSION_ID" "$HOOK_DATA" | ` +
    `curl -s -X POST "$CODEMAN_API_URL/api/hook-event" ` +
    `-H 'Content-Type: application/json' ` +
    `-H "X-Codeman-Hook-Secret: $(cat "$CODEMAN_HOOK_SECRET_FILE" 2>/dev/null)" ` +
    `--data @- ` +
    `2>/dev/null || true`;

  return {
    hooks: {
      Notification: [
        {
          matcher: 'idle_prompt',
          hooks: [{ type: 'command', command: curlCmd('idle_prompt'), timeout: HOOK_TIMEOUT_MS }],
        },
        {
          matcher: 'permission_prompt',
          hooks: [{ type: 'command', command: curlCmd('permission_prompt'), timeout: HOOK_TIMEOUT_MS }],
        },
        {
          matcher: 'elicitation_dialog',
          hooks: [{ type: 'command', command: curlCmd('elicitation_dialog'), timeout: HOOK_TIMEOUT_MS }],
        },
      ],
      Stop: [
        {
          hooks: [{ type: 'command', command: curlCmd('stop'), timeout: HOOK_TIMEOUT_MS }],
        },
      ],
      TeammateIdle: [
        {
          hooks: [{ type: 'command', command: curlCmd('teammate_idle'), timeout: HOOK_TIMEOUT_MS }],
        },
      ],
      TaskCompleted: [
        {
          hooks: [{ type: 'command', command: curlCmd('task_completed'), timeout: HOOK_TIMEOUT_MS }],
        },
      ],
    },
  };
}

/**
 * Remove a subset of env keys from .claude/settings.local.json.env if present.
 * Used during the disk→tmux-setenv migration: when the caller is actively setting
 * a fresh value for a Codeman-managed key, any stale disk entry for THAT KEY is
 * superseded and should be removed. Keys NOT in `keysToRemove` are left alone
 * (they may be user-managed). No-op if the file/keys don't exist.
 */
export async function stripCaseEnvKeys(casePath: string, keysToRemove: readonly string[]): Promise<void> {
  if (keysToRemove.length === 0) return;

  const settingsPath = join(casePath, '.claude', 'settings.local.json');
  await withSettingsLock(settingsPath, async () => {
    if (!existsSync(settingsPath)) return;

    let existing: Record<string, unknown>;
    try {
      existing = JSON.parse(await readFile(settingsPath, 'utf-8'));
    } catch {
      return; // Malformed — don't rewrite it
    }

    const env = existing.env as Record<string, string> | undefined;
    if (!env) return;

    let changed = false;
    for (const key of keysToRemove) {
      if (key in env) {
        delete env[key];
        changed = true;
      }
    }
    if (!changed) return;

    existing.env = env;
    await writeFile(settingsPath, JSON.stringify(existing, null, 2) + '\n');
  });
}

/**
 * Updates env vars in .claude/settings.local.json for the given case path.
 * Merges with existing env field; removes vars set to empty string.
 */
export async function updateCaseEnvVars(casePath: string, envVars: Record<string, string>): Promise<void> {
  const claudeDir = join(casePath, '.claude');
  const settingsPath = join(claudeDir, 'settings.local.json');
  await withSettingsLock(settingsPath, async () => {
    if (!existsSync(claudeDir)) {
      await mkdir(claudeDir, { recursive: true });
    }

    let existing: Record<string, unknown> = {};
    try {
      existing = JSON.parse(await readFile(settingsPath, 'utf-8'));
    } catch {
      existing = {};
    }

    const currentEnv = (existing.env as Record<string, string>) || {};
    for (const [key, value] of Object.entries(envVars)) {
      if (value) {
        currentEnv[key] = value;
      } else {
        delete currentEnv[key];
      }
    }
    existing.env = currentEnv;

    await writeFile(settingsPath, JSON.stringify(existing, null, 2) + '\n');
  });
}

/**
 * Updates the `model` field in .claude/settings.local.json for the given case path.
 * Pass a non-empty string to set, or empty/null to remove.
 */
export async function updateCaseModel(casePath: string, model: string | null): Promise<void> {
  const claudeDir = join(casePath, '.claude');
  const settingsPath = join(claudeDir, 'settings.local.json');
  await withSettingsLock(settingsPath, async () => {
    if (!existsSync(claudeDir)) {
      await mkdir(claudeDir, { recursive: true });
    }

    let existing: Record<string, unknown> = {};
    try {
      existing = JSON.parse(await readFile(settingsPath, 'utf-8'));
    } catch {
      existing = {};
    }

    if (model) {
      existing.model = model;
    } else {
      delete existing.model;
    }

    await writeFile(settingsPath, JSON.stringify(existing, null, 2) + '\n');
  });
}

/**
 * Writes hooks config to .claude/settings.local.json in the given case path.
 * Merges with existing file content, only touching the `hooks` key.
 */
export async function writeHooksConfig(casePath: string): Promise<void> {
  const claudeDir = join(casePath, '.claude');
  const settingsPath = join(claudeDir, 'settings.local.json');
  await withSettingsLock(settingsPath, async () => {
    if (!existsSync(claudeDir)) {
      await mkdir(claudeDir, { recursive: true });
    }

    let existing: Record<string, unknown> = {};
    try {
      existing = JSON.parse(await readFile(settingsPath, 'utf-8'));
    } catch {
      // If file is malformed or doesn't exist, start fresh
      existing = {};
    }

    const hooksConfig = generateHooksConfig();
    const merged = { ...existing, ...hooksConfig };

    await writeFile(settingsPath, JSON.stringify(merged, null, 2) + '\n');
  });
}

/**
 * Self-heal a case's hooks block so the COD-91 unconditional hook-secret gate keeps
 * accepting its hook events.
 *
 * `writeHooksConfig` only runs when a case is first CREATED. Cases created before the
 * X-Codeman-Hook-Secret header was added (COD-54, 2026-06-10) keep hook curls in their
 * settings.local.json that POST to /api/hook-event WITHOUT the secret — which, once the
 * gate requires it unconditionally (COD-91), silently 401 on a password-protected
 * install. This refreshes the hooks block so those stale curls regain the header.
 *
 * Deliberately surgical: regenerates ONLY when settings.local.json already contains
 * Codeman's own hook curls (they target `/api/hook-event`) that lack the secret header.
 * No-op when the file/hooks are absent (we never impose hooks on a user who removed
 * them), when the hooks aren't ours, or when the secret is already present — so it never
 * clobbers a user's customizations and is cheap enough to call on every Claude spawn.
 */
export async function refreshStaleHookSecret(casePath: string): Promise<void> {
  const settingsPath = join(casePath, '.claude', 'settings.local.json');
  if (!existsSync(settingsPath)) return;
  await withSettingsLock(settingsPath, async () => {
    let existing: Record<string, unknown>;
    try {
      existing = JSON.parse(await readFile(settingsPath, 'utf-8'));
    } catch {
      return; // malformed — leave it untouched (case-create owns the happy path)
    }
    const hooksJson = JSON.stringify(existing.hooks ?? null);
    const isOurs = hooksJson.includes('/api/hook-event');
    // The generated curl carries this header literal (see generateHooksConfig); its
    // absence on our own hooks means they predate COD-54 and need regenerating.
    const hasSecret = hooksJson.includes('X-Codeman-Hook-Secret');
    if (!isOurs || hasSecret) return;
    const merged = { ...existing, ...generateHooksConfig() };
    await writeFile(settingsPath, JSON.stringify(merged, null, 2) + '\n');
  });
}

/** Unique marker identifying Codeman's own statusLine command (vs a user's). */
const STATUSLINE_MARKER = '/api/status-telemetry';

/**
 * The plan-usage statusLine exporter command. Mirrors the hook `curlCmd` pattern:
 * reads Claude Code's statusline stdin JSON, POSTs `{sessionId,data}` to Codeman,
 * and prints the response body (a compact "⟳ 5h 15% · 7d 34%" footer) back to
 * stdout so the in-terminal statusline stays useful. Env vars resolve at runtime
 * (present in every managed session via tmux setenv), so the config is static.
 */
export function generateStatusLineCommand(): string {
  // `curl -sk`: CODEMAN_API_URL is loopback HTTPS with a self-signed cert in the
  // production setup; without -k curl returns 000 and the statusline shows
  // nothing. -k is safe here (loopback only). Falls back to a brand string so the
  // footer is never blank if Codeman is unreachable.
  return (
    `INPUT=$(cat 2>/dev/null || echo '{}'); ` +
    `printf '{"sessionId":"%s","data":%s}' "$CODEMAN_SESSION_ID" "$INPUT" | ` +
    `curl -sk -X POST "$CODEMAN_API_URL${STATUSLINE_MARKER}" ` +
    `-H 'Content-Type: application/json' ` +
    `-H "X-Codeman-Hook-Secret: $(cat "$CODEMAN_HOOK_SECRET_FILE" 2>/dev/null)" ` +
    `--data @- 2>/dev/null || echo codeman`
  );
}

/**
 * Add or remove Codeman's plan-usage statusLine exporter in
 * `.claude/settings.local.json`. Only ever touches a statusLine that is OURS
 * (command targets `/api/status-telemetry`), so a user's hand-authored
 * statusLine is never removed OR overwritten — on both the enable and disable
 * paths we bail out when an existing statusLine isn't ours. Callers gate on
 * Claude mode. Merges, preserving all other keys (hooks, env, model).
 */
export async function applyStatusLineConfig(casePath: string, enabled: boolean): Promise<void> {
  const claudeDir = join(casePath, '.claude');
  const settingsPath = join(claudeDir, 'settings.local.json');

  await withSettingsLock(settingsPath, async () => {
    let existing: Record<string, unknown> = {};
    if (existsSync(settingsPath)) {
      try {
        existing = JSON.parse(await readFile(settingsPath, 'utf-8'));
      } catch {
        return; // Malformed — don't rewrite it
      }
    }

    const current = existing.statusLine as { command?: unknown } | undefined;
    const isOurs = !!current && typeof current.command === 'string' && current.command.includes(STATUSLINE_MARKER);

    if (enabled) {
      const desired = generateStatusLineCommand();
      if (isOurs && current?.command === desired) return; // already current — skip rewrite
      if (current && !isOurs) return; // user has their OWN statusLine — never clobber it
      if (!existsSync(claudeDir)) await mkdir(claudeDir, { recursive: true });
      existing.statusLine = { type: 'command', command: desired }; // add, or update an out-of-date ours
    } else {
      if (!isOurs) return; // nothing of ours to remove (leave a user's own statusLine alone)
      delete existing.statusLine;
    }

    await writeFile(settingsPath, JSON.stringify(existing, null, 2) + '\n');
  });
}