/**
 * @file router-apply.js
 * @description Attaches an AI Router profile (see `ai-routers.js`) to one lane.
 *
 * The two CLIs are configured in different places, and the difference is
 * theirs, not a choice made here:
 *
 *  - **Claude Code** reads an `env` block out of the settings layers, so a
 *    router is eight env keys merged into the lane's own
 *    `.claude/settings.local.json`. `settings.local.json` and not
 *    `settings.json` because the value written includes an API key, and the
 *    `.local` file is the one Claude Code's own convention keeps out of git.
 *
 *  - **Codex** has no project-level config at all — `codex doctor` reports a
 *    single loaded file, `~/.codex/config.toml`. What it does have is
 *    `-p <name>`, which layers `$CODEX_HOME/<name>.config.toml` on top of that
 *    base. So a profile becomes a layer file, the base is never touched, and
 *    the lane's spawn passes the flag. Codex takes the key from the environment
 *    variable named by `env_key`, so the key stays out of the file entirely and
 *    reaches the pane through tmux's own `-e`, never as typed text.
 *
 * Target directories come from the lane row, never from a request body — the
 * same narrowing every other lane write path in this codebase uses.
 *
 * Attaching COPIES a profile, so the store is not the single source of truth
 * once a lane exists. `reapplyToLanes`/`detachFromLanes` are what keep an edit
 * or a delete in Settings from being silently inert on the lanes using it.
 *
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("node:fs");
const path = require("node:path");

const routers = require("./ai-routers");
const { patchSettings } = require("./cc-mutate");
const { getCodexHome } = require("./codex-home");
const { lanesByRouter, setRouterProfile } = require("./lanes");

/**
 * The env var Codex is told to read the router key from. One fixed name rather
 * than one per profile: a Codex pane runs exactly one profile, so a second name
 * would only create the chance of the wrong one being set.
 */
const CODEX_KEY_ENV = "AGENTHUB_ROUTER_KEY";

/** The eight keys this feature owns in a lane's settings file, and nothing else. */
function envForProfile(profile) {
  return {
    ANTHROPIC_BASE_URL: profile.baseUrl,
    ANTHROPIC_AUTH_TOKEN: profile.apiKey,
    ANTHROPIC_MODEL: profile.model,
    ANTHROPIC_DEFAULT_OPUS_MODEL: profile.models.opus,
    ANTHROPIC_DEFAULT_SONNET_MODEL: profile.models.sonnet,
    ANTHROPIC_DEFAULT_HAIKU_MODEL: profile.models.haiku,
    ANTHROPIC_SMALL_FAST_MODEL: profile.models.smallFast,
    CLAUDE_CODE_SUBAGENT_MODEL: profile.models.subagent,
  };
}

/**
 * Read a profile, or resolve to null when it has since been deleted. Used on
 * the spawn path, where a missing profile must degrade the lane to its base
 * configuration rather than refuse to start it.
 */
function readOrNull(name) {
  if (!name || name === routers.BUILTIN_NAME) return null;
  try {
    return routers.getRouter(name);
  } catch {
    return null;
  }
}

/**
 * The lane's own git directory. For a normal clone that is `<cwd>/.git`; for a
 * LINKED WORKTREE — which is what every managed lane is — `.git` is a pointer
 * FILE, and joining `info/exclude` onto it names a path that cannot exist.
 *
 * @returns {string|null} absolute git dir, or null when this is not a repo
 */
function gitDirOf(laneDir) {
  const dotGit = path.join(laneDir, ".git");
  let stat;
  try {
    stat = fs.statSync(dotGit);
  } catch {
    return null; // not a git repo — a perfectly normal adopted directory
  }
  if (stat.isDirectory()) return dotGit;
  const match = fs.readFileSync(dotGit, "utf8").match(/^gitdir:\s*(.+)$/m);
  return match ? path.resolve(laneDir, match[1].trim()) : null;
}

/**
 * Idempotently keep `.claude/settings.local.json` out of git, for two reasons
 * that both matter:
 *
 *  - `agenthub lanes reset` runs `git clean -fd` (`server/lib/worktree.js`).
 *    Without `-x` that spares IGNORED files only, so an untracked settings file
 *    is deleted and the lane silently loses its router.
 *  - The file holds an API key. Untracked means `git add -A` can commit it.
 *
 * Best effort: a lane that is not a repo, or a git dir that cannot be written,
 * must not fail an otherwise-successful attach.
 */
function excludeSettingsFromGit(laneDir) {
  // The backup directory beside it, for the same reason plus one more: those
  // copies hold the API key too, and they are what a user sees as a dozen
  // untracked files appearing in their project while they switch routers.
  const lines = [".claude/settings.local.json", ".claude/.cc-config-backups/"];
  try {
    const gitDir = gitDirOf(laneDir);
    if (!gitDir) return;
    const excludePath = path.join(gitDir, "info", "exclude");
    fs.mkdirSync(path.dirname(excludePath), { recursive: true });
    let existing = fs.existsSync(excludePath) ? fs.readFileSync(excludePath, "utf8") : "";
    const present = new Set(existing.split("\n"));
    const missing = lines.filter((line) => !present.has(line));
    if (missing.length === 0) return;
    if (existing && !existing.endsWith("\n")) existing += "\n";
    fs.writeFileSync(excludePath, `${existing}${missing.join("\n")}\n`);
  } catch {
    /* best effort — see above */
  }
}

/**
 * Merge the eight keys into the lane's settings, leaving every other key —
 * including every other env var — exactly as it was.
 *
 * `patchSettings` does this already and does it better than a local merge
 * would: per-key deep merge, a size ceiling, `__proto__`-style segments
 * refused, an atomic write, a timestamped backup, and a file that is not valid
 * JSON reported (`EBADJSON`) instead of overwritten. It resolves
 * `project-local` to exactly `<cwd>/.claude/settings.local.json`. The
 * caller-chosen-cwd rule it is written against is a ROUTE rule; `lane.cwd`
 * comes from the DB row, which is the shape that rule allows.
 *
 * What it does not do is set a mode, because nothing else it writes holds a
 * secret. This one does, so the file and the backup it just made of the
 * previous one are both tightened afterwards.
 */
function applyToClaudeLane(lane, profile) {
  // Native is not simply "no keys". The two halves go opposite ways:
  //
  //  - The CONNECTION pair is BLANKED, not removed. An absent key at project
  //    scope means the user-level one applies, so dropping these would let a
  //    user-level router take over a lane that explicitly asked for native.
  //  - The MODEL names are REMOVED. Writing them would pin every lane — including
  //    one created by a user who never opened this tab — to whatever names this
  //    file shipped with, overriding the user-level choice that is the actual
  //    source of truth for native.
  const env = envForProfile(profile);
  const set = {};
  let unset = [];
  if (profile.builtin) {
    const connection = ["ANTHROPIC_BASE_URL", "ANTHROPIC_AUTH_TOKEN"];
    for (const key of connection) set[`env.${key}`] = "";
    unset = Object.keys(env)
      .filter((key) => !connection.includes(key))
      .map((key) => `env.${key}`);
  } else {
    for (const [key, value] of Object.entries(env)) set[`env.${key}`] = value;
  }

  const result = patchSettings({ scope: "project-local", cwd: lane.cwd, set, unset });
  // Both branches, not just the router one. A native lane's blanked connection
  // pair is load-bearing too — `git clean -fd` deleting it would let a
  // user-level router quietly take over a lane that asked for native.
  excludeSettingsFromGit(lane.cwd);
  for (const file of [result.path, result.backupPath]) {
    if (!file) continue;
    try {
      fs.chmodSync(file, 0o600);
    } catch {
      // Best effort: a write that landed must not be reported as a failure
      // because the mode could not be tightened afterwards.
    }
  }
  return { tool: "claude", file: result.path, profile: profile.name };
}

/** TOML string literal — router names and URLs are validated, quotes are not free. */
function tomlString(value) {
  return `"${String(value).replace(/\\/g, "\\\\").replace(/"/g, '\\"')}"`;
}

/**
 * Write `$CODEX_HOME/<name>.config.toml`, the layer `codex -p <name>` loads on
 * top of the base config. The base file is never read or written here.
 */
function applyToCodexLane(lane, profile) {
  const file = path.join(getCodexHome(), `${profile.name}.config.toml`);
  const body =
    `# Written by AgentHub — AI Router profile ${profile.label}.\n` +
    `# Loaded by \`codex -p ${profile.name}\`; the base config.toml is untouched.\n` +
    `model = ${tomlString(profile.model)}\n` +
    `model_provider = ${tomlString(profile.name)}\n\n` +
    `[model_providers.${profile.name}]\n` +
    `name = ${tomlString(profile.label)}\n` +
    `base_url = ${tomlString(profile.baseUrl)}\n` +
    // `env_key` only when there is a key to name. A local router (the 9Router
    // reference config is exactly this) needs none, and naming a variable that
    // is never set makes Codex refuse to start.
    (profile.apiKey ? `env_key = ${tomlString(CODEX_KEY_ENV)}\n` : "") +
    // Not "chat": codex-cli 0.149 rejects it outright — `wire_api = "chat" is
    // no longer supported`, a hard config error before the first request. The
    // user's own working 9Router provider uses "responses" too.
    `wire_api = "responses"\n`;

  fs.mkdirSync(path.dirname(file), { recursive: true });
  fs.writeFileSync(file, body, { mode: 0o600 });
  return { tool: "codex", file, profile: profile.name };
}

/**
 * Attach `profileName` to `lane`. Called once, when the lane is created.
 *
 * @param {{id:number, cwd:string, tool:string}} lane the lane row
 * @param {string} profileName a saved profile's name, or `"native"`
 */
function applyRouterToLane(lane, profileName) {
  const profile = routers.getRouter(profileName); // throws ENOTFOUND
  if (lane.tool === "codex") {
    // Native is the base config as it already stands. A layer that overrode
    // nothing would still shadow whatever model the user set in the base.
    if (profile.builtin) return { tool: "codex", file: null, profile: profile.name };
    return applyToCodexLane(lane, profile);
  }
  return applyToClaudeLane(lane, profile);
}

/**
 * Extra argv for a lane's spawn. Codex needs `-p <name>`; a Claude lane needs
 * nothing, its settings file already carries the router.
 * @returns {string[]}
 */
function routerArgvForSpawn(lane) {
  if (!lane || lane.tool !== "codex") return [];
  const profile = readOrNull(lane.router_profile);
  return profile ? ["-p", profile.name] : [];
}

/**
 * Extra environment for a lane's spawn — the key Codex's `env_key` names.
 * @returns {Record<string,string>}
 */
function routerEnvForSpawn(lane) {
  if (!lane || lane.tool !== "codex") return {};
  const profile = readOrNull(lane.router_profile);
  return profile && profile.apiKey ? { [CODEX_KEY_ENV]: profile.apiKey } : {};
}

/**
 * Re-run the attach for every lane already on `profileName`.
 *
 * Attaching COPIES the profile — a claude lane's key and base URL live in its
 * own settings file from then on. So an edit that stopped here would be inert
 * where it matters most: rotating a leaked key in Settings would leave every
 * claude lane authenticating with the revoked one, forever, with no in-product
 * way to notice or fix it.
 *
 * Per-lane best effort: a lane whose directory is gone, or whose settings file
 * a human has since broken, must not fail the edit for every other lane.
 *
 * @returns {{updated:number, failed:string[]}}
 */
function reapplyToLanes(profileName) {
  const failed = [];
  let updated = 0;
  for (const lane of lanesByRouter(profileName)) {
    try {
      applyRouterToLane(lane, profileName);
      updated += 1;
    } catch (e) {
      failed.push(`${lane.id} (${lane.title || lane.cwd}): ${e.code || e.message}`);
    }
  }
  return { updated, failed };
}

/**
 * Detach `profileName` from every lane using it, and delete the Codex layer
 * file it wrote.
 *
 * Deleting a profile has to reach the lanes for the same reason an edit does,
 * and more urgently: a claude lane keeps the deleted router's key and base URL
 * in its settings file and would go on routing to a dead endpoint with a key
 * the user believes they have removed. Each lane is reset to native — which now
 * UNSETS those keys — and its `router_profile` cleared.
 *
 * The layer file matters too: left behind, a later profile that slugifies to
 * the same name silently inherits this one's `base_url`.
 */
function detachFromLanes(profileName) {
  const failed = [];
  let updated = 0;
  for (const lane of lanesByRouter(profileName)) {
    try {
      applyRouterToLane(lane, routers.BUILTIN_NAME);
      setRouterProfile(lane.id, null);
      updated += 1;
    } catch (e) {
      failed.push(`${lane.id} (${lane.title || lane.cwd}): ${e.code || e.message}`);
    }
  }
  try {
    fs.rmSync(path.join(getCodexHome(), `${profileName}.config.toml`), { force: true });
  } catch {
    /* best effort — an orphan layer is a leak, not a failure to report */
  }
  return { updated, failed };
}

module.exports = {
  applyRouterToLane,
  reapplyToLanes,
  detachFromLanes,
  routerArgvForSpawn,
  routerEnvForSpawn,
  CODEX_KEY_ENV,
};