import os from "node:os";
import path from "node:path";
import { existsSync, mkdirSync, writeFileSync, copyFileSync } from "node:fs";
import { apiFetch } from "../api.mjs";
import { createPrompt, printSuccess, printError, printInfo, printHeading } from "../io.mjs";
import { t } from "../i18n.mjs";

/**
 * `omniroute configure <cli>` — interactive provider+model picker that writes a
 * local CLI config pointed at the ACTIVE OmniRoute context (local or remote).
 *
 * The model catalog comes from the active context's GET /v1/models, so when you
 * are in remote mode (`omniroute connect ...`) you pick from the remote server's
 * live models and the profile is written on THIS machine.
 *
 * v1 targets the Codex CLI (writes ~/.codex/<name>.config.toml). The credential
 * is referenced by env var (OMNIROUTE_API_KEY) — never written to disk.
 */

const SUPPORTED = ["codex"];

/** Derive a short, filesystem-safe profile name from a model id. */
export function profileNameFromModel(modelId) {
  const afterProvider = String(modelId).includes("/")
    ? String(modelId).split("/").slice(1).join("/")
    : String(modelId);
  return afterProvider.replace(/[^a-zA-Z0-9]+/g, "").toLowerCase() || "model";
}

/** Provider id for a catalog entry: explicit owned_by, else the id prefix. */
function providerOf(entry) {
  if (entry && typeof entry.owned_by === "string" && entry.owned_by) return entry.owned_by;
  const id = typeof entry === "string" ? entry : entry?.id || "";
  return id.includes("/") ? id.split("/")[0] : "(none)";
}

function contextWindowOf(entry) {
  for (const c of [entry?.context_length, entry?.max_context_window_tokens]) {
    if (typeof c === "number" && Number.isFinite(c) && c > 0) return c;
  }
  return null;
}

async function fetchModels(globalOpts) {
  const res = await apiFetch("/v1/models", { ...globalOpts, acceptNotOk: true });
  if (!res.ok) {
    let msg = `HTTP ${res.status}`;
    try {
      const b = await res.json();
      msg = b?.error?.message || b?.error || msg;
    } catch {
      /* ignore */
    }
    throw new Error(`Could not fetch models: ${msg}`);
  }
  const body = await res.json();
  const list = Array.isArray(body) ? body : body.data || body.models || [];
  return list.filter((m) => (typeof m === "string" ? m : m?.id));
}

function buildCodexProfile(modelId, ctx) {
  const lines = [
    `# codex --profile ${profileNameFromModel(modelId)}`,
    `# ${modelId} — generated by 'omniroute configure codex'`,
    `model                          = "${modelId}"`,
    `model_provider                 = "omniroute"`,
  ];
  if (ctx && ctx > 0) {
    const compact = Math.floor(ctx * 0.85);
    lines.push(`model_context_window           = ${ctx}`);
    lines.push(`model_auto_compact_token_limit = ${compact}`);
  }
  return lines.join("\n") + "\n";
}

async function configureCodex(modelId, ctxWindow, opts) {
  const codexHome = opts.codexHome || path.join(os.homedir(), ".codex");
  if (!existsSync(codexHome)) mkdirSync(codexHome, { recursive: true });
  const profile = opts.name || profileNameFromModel(modelId);
  const filePath = path.join(codexHome, `${profile}.config.toml`);
  if (existsSync(filePath)) {
    copyFileSync(filePath, `${filePath}.bak`);
  }
  writeFileSync(filePath, buildCodexProfile(modelId, ctxWindow), "utf8");
  printSuccess(`Wrote ${filePath}`);
  printInfo(`Use it:  codex --profile ${profile}`);
  printInfo("Prereq: ~/.codex/config.toml must define the [model_providers.omniroute] block");
  printInfo("        (run the Codex setup once — see docs/guides/CODEX-CLI-CONFIGURATION.md).");
}

export async function runConfigureCommand(cli, opts = {}, cmd) {
  const target = String(cli || "").toLowerCase();
  if (!SUPPORTED.includes(target)) {
    printError(`Unsupported CLI '${cli}'. Supported: ${SUPPORTED.join(", ")}.`);
    return 2;
  }
  const globalOpts = cmd ? cmd.optsWithGlobals() : {};

  let models;
  try {
    models = await fetchModels(globalOpts);
  } catch (e) {
    printError(e instanceof Error ? e.message : String(e));
    return 1;
  }
  if (!models.length) {
    printError("The server returned no models.");
    return 1;
  }

  // Resolve model: explicit flags or interactive pick.
  let chosenId = opts.model;
  if (chosenId && opts.provider && !chosenId.includes("/")) {
    chosenId = `${opts.provider}/${chosenId}`;
  }

  if (!chosenId) {
    const ids = models.map((m) => (typeof m === "string" ? m : m.id));
    const providers = [...new Set(models.map(providerOf))].sort();
    const prompt = createPrompt();
    try {
      printHeading("Configure Codex CLI");
      let providerList = providers;
      if (opts.provider) {
        providerList = providers.filter((p) => p === opts.provider);
      } else {
        printInfo(`Providers: ${providers.join(", ")}`);
        const p = await prompt.ask("Provider");
        if (p) providerList = providers.filter((x) => x === p);
      }
      const inProvider = ids.filter((id) => providerList.includes(providerOf(byId(models, id))));
      const candidates = inProvider.length ? inProvider : ids;
      printInfo(`Models: ${candidates.slice(0, 40).join(", ")}${candidates.length > 40 ? " …" : ""}`);
      chosenId = await prompt.ask("Model id");
    } finally {
      prompt.close();
    }
  }

  if (!chosenId) {
    printError("No model selected.");
    return 2;
  }
  const entry = byId(models, chosenId);
  if (!entry) {
    printError(`Model '${chosenId}' is not in the catalog.`);
    return 2;
  }
  const ctxWindow = contextWindowOf(entry);

  if (target === "codex") {
    await configureCodex(chosenId, ctxWindow, opts);
  }
  return 0;
}

function byId(models, id) {
  for (const m of models) {
    const mid = typeof m === "string" ? m : m.id;
    if (mid === id) return m;
  }
  return null;
}

export function registerConfigure(program) {
  program
    .command("configure <cli>")
    .description(
      t("configure.description") ||
        "Pick a provider+model from the active server and write a local CLI config (v1: codex)"
    )
    .option("--provider <id>", "Provider id (skips the interactive provider prompt)")
    .option("--model <id>", "Model id (skips the interactive model prompt)")
    .option("--name <name>", "Profile name to write (default: derived from model)")
    .option("--codex-home <dir>", "Codex home dir (default: ~/.codex)")
    .action(async (cli, opts, cmd) => {
      const code = await runConfigureCommand(cli, opts, cmd);
      if (code !== 0) process.exit(code);
    });
}