import simpleGit, { SimpleGit } from "simple-git";
import fs from "fs/promises";
import { REPOS, GIT_PROVIDER_URL, type RepoName } from "../config/repos.js";
import { getRepoPath, readConfig } from "./workspace.service.js";
import { broadcast } from "./ws.service.js";

function git(repoPath: string): SimpleGit {
  return simpleGit(repoPath);
}

function getRepoDef(name: RepoName) {
  const def = REPOS.find((r) => r.name === name);
  if (!def) throw new Error(`Unknown repo: ${name}`);
  return def;
}

export async function cloneRepo(
  repoUrl: string,
  targetDir: string,
  opts?: { depth?: number; branch?: string },
) {
  const args: string[] = [];
  if (opts?.depth) args.push("--depth", String(opts.depth));
  if (opts?.branch) args.push("--branch", opts.branch);
  await simpleGit().clone(repoUrl, targetDir, args);
}

export async function getRepoStatus(repoPath: string) {
  const g = git(repoPath);
  const status = await g.status();
  let ahead = 0;
  let behind = 0;
  try {
    const raw = await g.raw(["rev-list", "--left-right", "--count", `HEAD...@{u}`]);
    const parts = raw.trim().split(/\s+/);
    ahead = parseInt(parts[0], 10) || 0;
    behind = parseInt(parts[1], 10) || 0;
  } catch {
    // no upstream tracking set
  }
  return {
    modified: status.modified,
    staged: status.staged,
    untracked: status.not_added,
    ahead,
    behind,
    branch: status.current || "unknown",
  };
}

export async function pull(repoPath: string) {
  const g = git(repoPath);
  return g.pull();
}

const COMMIT_PATTERN = /^(feat|fix|refactor|docs|chore|test|style|perf|ci|build|revert)(\(.+\))?: .{1,100}$/;

export function validateCommitMessage(message: string): { valid: boolean; error?: string } {
  const firstLine = message.split("\n")[0];
  if (!COMMIT_PATTERN.test(firstLine)) {
    return {
      valid: false,
      error: `Invalid format. Expected: type(scope): description. Valid types: feat, fix, refactor, docs, chore, test, style, perf, ci, build, revert`,
    };
  }
  return { valid: true };
}

export async function commitFiles(repoPath: string, message: string, files?: string[]) {
  const validation = validateCommitMessage(message);
  if (!validation.valid) {
    throw new Error(validation.error);
  }

  const g = git(repoPath);
  if (files && files.length > 0) {
    await g.add(files);
  } else {
    await g.add("-A");
  }
  return g.commit(message);
}

export async function push(repoPath: string) {
  const g = git(repoPath);
  return g.push();
}

export async function fetchUpstream(repoPath: string): Promise<number> {
  const g = git(repoPath);
  await g.fetch("upstream");
  const branch = (await g.status()).current || "main";
  try {
    const raw = await g.raw(["rev-list", "--count", `HEAD..upstream/${branch}`]);
    return parseInt(raw.trim(), 10) || 0;
  } catch {
    return 0;
  }
}

export async function mergeUpstream(repoPath: string, branch: string) {
  const g = git(repoPath);
  return g.merge([`upstream/${branch}`]);
}

export async function getDiff(repoPath: string, file?: string) {
  const g = git(repoPath);
  if (file) {
    return g.diff(["HEAD", "--", file]);
  }
  return g.diff(["HEAD"]);
}

function getCloneUrl(token: string, user: string, repoName: string, provider: string): string {
  const host = provider === "github" ? "github.com" : new URL(GIT_PROVIDER_URL).host;
  return `https://${token}@${host}/${user}/${repoName}.git`;
}

function getUpstreamUrl(owner: string, repo: string, provider: string, token?: string): string {
  if (provider === "github") {
    return `https://github.com/${owner}/${repo}.git`;
  }
  const host = new URL(GIT_PROVIDER_URL).host;
  if (token) {
    return `https://${token}@${host}/${owner}/${repo}.git`;
  }
  return `https://${host}/${owner}/${repo}.git`;
}

export async function setupClone(repoName: RepoName) {
  const config = await readConfig();
  const pat = config.githubPat;
  if (!pat) throw new Error("Git provider token not configured");

  const repoDef = getRepoDef(repoName);
  const [upOwner, upRepo] = repoDef.upstream.split("/");
  const targetDir = getRepoPath(repoName);

  try {
    await fs.access(targetDir);
    throw new Error(`Repo directory already exists: ${targetDir}`);
  } catch (err: unknown) {
    if (err instanceof Error && err.message.startsWith("Repo directory")) throw err;
  }

  if (repoDef.provider === "github") {
    const upstreamUrl = getUpstreamUrl(upOwner, upRepo, "github");
    await cloneRepo(upstreamUrl, targetDir, { branch: repoDef.branch, depth: 1 });
  } else {
    const { validateToken } = await import("./git-provider.service.js");
    const { login } = await validateToken(pat as string);
    const forkUrl = getCloneUrl(pat as string, login, upRepo, repoDef.provider);
    const upstreamUrl = getUpstreamUrl(upOwner, upRepo, repoDef.provider, pat as string);
    await cloneRepo(forkUrl, targetDir, { branch: repoDef.branch, depth: 1 });
    const g = git(targetDir);
    await g.addRemote("upstream", upstreamUrl);
    await g.fetch("upstream");
  }

  return { path: targetDir, branch: repoDef.branch };
}

export async function listReposWithStatus() {
  const results: Array<{
    name: string;
    branch: string;
    upstream: string;
    cloned: boolean;
    status?: Awaited<ReturnType<typeof getRepoStatus>>;
  }> = [];

  for (const repo of REPOS) {
    const repoPath = getRepoPath(repo.name);
    let cloned = false;
    try {
      await fs.access(repoPath);
      cloned = true;
    } catch {
      // not cloned
    }

    if (cloned) {
      try {
        const status = await getRepoStatus(repoPath);
        results.push({ name: repo.name, branch: repo.branch, upstream: repo.upstream, cloned, status });
      } catch {
        results.push({ name: repo.name, branch: repo.branch, upstream: repo.upstream, cloned });
      }
    } else {
      results.push({ name: repo.name, branch: repo.branch, upstream: repo.upstream, cloned });
    }
  }

  return results;
}

const lastKnownBehind = new Map<string, number>();
let pollingInterval: ReturnType<typeof setInterval> | null = null;

export function startUpstreamPolling(intervalMs: number = 900000): void {
  if (pollingInterval) return;
  pollingInterval = setInterval(async () => {
    for (const repo of REPOS) {
      try {
        const repoPath = getRepoPath(repo.name);
        await fs.access(repoPath);
        const behind = await fetchUpstream(repoPath);
        const prev = lastKnownBehind.get(repo.name) || 0;
        if (behind !== prev) {
          lastKnownBehind.set(repo.name, behind);
          if (behind > 0) {
            broadcast("git", "upstream-update", { repo: repo.name, behind });
          }
        }
      } catch {
        // repo not cloned or fetch failed
      }
    }
  }, intervalMs);
}

export function stopUpstreamPolling(): void {
  if (pollingInterval) {
    clearInterval(pollingInterval);
    pollingInterval = null;
  }
}