'use strict';

const fs = require('node:fs/promises');
const path = require('node:path');
const { matchRemoteToRepository, repositoryKey } = require('../shared/repository-match.cjs');

const SKIP_DIRECTORIES = new Set([
  '.git', '.svn', '.hg', 'node_modules', '.next', '.nuxt', 'dist', 'build', 'coverage',
  '.cache', '.venv', 'venv', '__pycache__', '$RECYCLE.BIN', 'System Volume Information'
]);

async function mapLimit(items, limit, mapper) {
  const output = new Array(items.length);
  let cursor = 0;
  const workers = Array.from({ length: Math.min(limit, items.length) }, async () => {
    while (cursor < items.length) {
      const index = cursor++;
      output[index] = await mapper(items[index], index);
    }
  });
  await Promise.all(workers);
  return output;
}

class RepositoryService {
  constructor(store, gitService, giteaService, diagnostics = null) {
    this.store = store;
    this.git = gitService;
    this.gitea = giteaService;
    this.diagnostics = diagnostics;
    this.lastKnownLocalPaths = [];
    this.lastKnownRemoteRepositories = [];
    this.lastSuccessfulRemoteRefreshAt = null;
    this.lastRemoteRefreshAtMs = 0;
    this.lastDiscoveredPaths = [];
    this.lastDiscoveryAtMs = 0;
    this.refreshPromise = null;
    this.lastResult = null;
  }

  async discoverInRoot(root, maxDepth = 4) {
    const found = [];
    const seen = new Set();

    const visit = async (directory, depth) => {
      let real;
      try { real = await fs.realpath(directory); } catch { return; }
      if (seen.has(real)) return;
      seen.add(real);

      const gitMarker = path.join(directory, '.git');
      const marker = await fs.stat(gitMarker).catch(() => null);
      if (marker) {
        found.push(real);
        return;
      }
      if (depth >= maxDepth) return;

      let entries;
      try { entries = await fs.readdir(real, { withFileTypes: true }); } catch { return; }
      // Directory entries report as a symbolic link instead of a directory, which
      // is how Windows junctions surface. Skipping those made a project folder
      // that is mapped through a junction invisible; visit() resolves each entry
      // and the `seen` set above keeps links that point back into the tree from
      // being scanned twice.
      await mapLimit(entries
        .filter((entry) => (entry.isDirectory() || entry.isSymbolicLink()) && !SKIP_DIRECTORIES.has(entry.name)), 12,
      (entry) => visit(path.join(real, entry.name), depth + 1));
    };

    await visit(root, 0);
    return found;
  }

  async discoverAll(roots) {
    const grouped = await mapLimit((roots || []).filter(Boolean), 4, (root) => this.discoverInRoot(root));
    return [...new Set(grouped.flat())];
  }

  async getLocalDescriptors(paths) {
    return mapLimit(paths, 5, async (localPath) => {
      try {
        const status = await this.git.status(localPath);
        return { localPath: status.root, remoteUrl: status.remoteUrl, status };
      } catch (error) {
        return { localPath, remoteUrl: '', status: null, error: error.message };
      }
    });
  }

  getWatchPaths() {
    return [...this.lastKnownLocalPaths];
  }

  async getRemoteRepositories({ force = false } = {}) {
    if (!this.store.data.gitea.baseUrl || !this.store.getToken()) {
      this.lastKnownRemoteRepositories = [];
      this.lastSuccessfulRemoteRefreshAt = null;
      return { repositories: [], stale: false, error: null };
    }

    if (!force && this.lastSuccessfulRemoteRefreshAt && Date.now() - this.lastRemoteRefreshAtMs < 15_000) {
      return {
        repositories: this.lastKnownRemoteRepositories.map((repository) => ({ ...repository })),
        stale: false,
        error: null,
        cached: true
      };
    }

    try {
      const repositories = await this.gitea.listRepositories();
      this.lastKnownRemoteRepositories = repositories.map((repository) => ({ ...repository }));
      this.lastSuccessfulRemoteRefreshAt = new Date().toISOString();
      this.lastRemoteRefreshAtMs = Date.now();
      return { repositories, stale: false, error: null };
    } catch (error) {
      if (!this.lastSuccessfulRemoteRefreshAt) throw error;
      await this.diagnostics?.warning('repositories.remote-refresh.degraded', {
        message: error.message,
        cachedCount: this.lastKnownRemoteRepositories.length,
        lastSuccessfulAt: this.lastSuccessfulRemoteRefreshAt
      });
      return {
        repositories: this.lastKnownRemoteRepositories.map((repository) => ({ ...repository })),
        stale: true,
        error: error.message
      };
    }
  }

  async getDiscoveredPaths({ force = false } = {}) {
    if (!force && this.lastDiscoveryAtMs && Date.now() - this.lastDiscoveryAtMs < 30_000) {
      return [...this.lastDiscoveredPaths];
    }
    const paths = await this.discoverAll(this.store.data.workspaceRoots);
    this.lastDiscoveredPaths = [...paths];
    this.lastDiscoveryAtMs = Date.now();
    return paths;
  }

  // Resolving a single repository used to go through a full refresh, which runs
  // `git status` for every discovered repository. Handlers that act on one
  // repository only need that one, so its local state is read directly. Anything
  // this cannot answer confidently still falls back to the full scan.
  async resolveByFullName(fullName) {
    const name = String(fullName || '').trim();
    if (!name) return null;
    const fromFullRefresh = async () => (await this.refresh()).find((item) => item.fullName === name) || null;

    const remoteResult = await this.getRemoteRepositories({});
    const remote = remoteResult.repositories.find((item) => item.full_name === name);
    if (!remote) return fromFullRefresh();

    const explicitPath = this.store.data.repositoryMappings[repositoryKey(remote)];
    const knownPath = explicitPath || (this.lastResult || []).find((item) => item.fullName === name)?.localPath || null;
    // Without a known path the link can still exist through remote-URL matching,
    // which only the discovery pass can establish.
    if (!knownPath && !this.lastResult) return fromFullRefresh();

    const local = knownPath ? (await this.getLocalDescriptors([knownPath]))[0] : null;
    const profiles = this.store.getDeploymentProfiles(remote.full_name).map((profile) => ({
      ...profile,
      state: this.store.getDeploymentState(profile.id)
    }));
    return {
      ...this.decorate(remote, local, profiles),
      remoteStale: remoteResult.stale,
      remoteRefreshError: remoteResult.error,
      remoteLastRefreshedAt: this.lastSuccessfulRemoteRefreshAt
    };
  }

  async refresh(options = {}) {
    if (this.refreshPromise) return this.refreshPromise;
    this.refreshPromise = this.performRefresh(options).finally(() => { this.refreshPromise = null; });
    return this.refreshPromise;
  }

  async performRefresh({ force = false } = {}) {
    const started = Date.now();
    const remoteResult = await this.getRemoteRepositories({ force });
    const remoteRepositories = remoteResult.repositories;

    const discoveredPaths = await this.getDiscoveredPaths({ force });
    const mappedPaths = Object.values(this.store.data.repositoryMappings || {});
    const localPaths = [...new Set([...discoveredPaths, ...mappedPaths])];
    const localDescriptors = await this.getLocalDescriptors(localPaths);
    this.lastKnownLocalPaths = localDescriptors.filter((item) => item.status).map((item) => item.status.root);

    const usedLocalPaths = new Set();
    const repositories = [];

    for (const remote of remoteRepositories) {
      const key = repositoryKey(remote);
      const explicitPath = this.store.data.repositoryMappings[key];
      let local = explicitPath ? localDescriptors.find((item) => path.resolve(item.localPath) === path.resolve(explicitPath)) : null;
      if (!local) local = localDescriptors.find((item) => !usedLocalPaths.has(item.localPath) && matchRemoteToRepository(item.remoteUrl, [remote]));
      if (local) usedLocalPaths.add(local.localPath);

      const profiles = this.store.getDeploymentProfiles(remote.full_name).map((profile) => ({
        ...profile,
        state: this.store.getDeploymentState(profile.id)
      }));
      repositories.push({
        ...this.decorate(remote, local, profiles),
        remoteStale: remoteResult.stale,
        remoteRefreshError: remoteResult.error,
        remoteLastRefreshedAt: this.lastSuccessfulRemoteRefreshAt
      });
    }

    for (const local of localDescriptors.filter((item) => !usedLocalPaths.has(item.localPath))) {
      const name = path.basename(local.localPath);
      repositories.push({
        id: `local:${local.localPath}`,
        name,
        fullName: name,
        owner: { login: 'local' },
        description: 'Local repository not matched to Gitea',
        private: true,
        defaultBranch: local.status?.branch.head || 'main',
        htmlUrl: null,
        cloneUrl: null,
        sshUrl: null,
        preferredCloneUrl: null,
        localPath: local.localPath,
        localStatus: local.status,
        linkState: 'unmatched-local',
        deploymentProfiles: [],
        readyToDeploy: false,
        favorite: false,
        attention: Boolean(local.error),
        attentionReason: local.error || null
      });
    }

    const sorted = repositories.sort((a, b) => {
      const score = (repo) => (repo.attention ? 100 : 0)
        + (repo.localStatus?.counts.changed ? 50 : 0)
        + (repo.localStatus?.branch.ahead ? 30 : 0)
        + (repo.readyToDeploy ? 20 : 0)
        + (repo.favorite ? 5 : 0);
      return score(b) - score(a) || a.fullName.localeCompare(b.fullName);
    });
    await this.diagnostics?.debug('repositories.refresh.completed', {
      durationMs: Date.now() - started,
      remoteCount: remoteRepositories.length,
      remoteStale: remoteResult.stale,
      remoteCached: remoteResult.cached === true,
      discoveredCount: discoveredPaths.length,
      linkedCount: sorted.filter((item) => item.localPath).length,
      attentionCount: sorted.filter((item) => item.attention).length,
      readyToDeployCount: sorted.filter((item) => item.readyToDeploy).length
    });
    this.lastResult = sorted;
    return sorted;
  }

  decorate(remote, local, profiles) {
    const status = local?.status || null;
    const hasChanges = Boolean(status?.counts.changed);
    const ahead = status?.branch.ahead || 0;
    const behind = status?.branch.behind || 0;
    const conflict = Boolean(status?.counts.conflicts);
    const profileForBranch = profiles.find((profile) => profile.branch === status?.branch.head);
    const synchronized = Boolean(profileForBranch && status?.head && status?.branch.upstream && !hasChanges && ahead === 0 && behind === 0);
    const alreadyLiveAndHealthy = Boolean(
      synchronized
      && profileForBranch?.state?.liveSha === status.head
      && profileForBranch?.state?.healthy !== false
    );
    const readyToDeploy = synchronized && !alreadyLiveAndHealthy;
    const key = String(remote.full_name || '').toLowerCase();
    const preferredCloneUrl = this.store.data.preferences.preferredCloneProtocol === 'ssh'
      ? (remote.ssh_url || remote.clone_url)
      : (remote.clone_url || remote.ssh_url);
    return {
      id: remote.id,
      name: remote.name,
      fullName: remote.full_name,
      owner: remote.owner,
      description: remote.description || '',
      private: remote.private,
      defaultBranch: remote.default_branch || 'main',
      htmlUrl: remote.html_url,
      cloneUrl: remote.clone_url,
      sshUrl: remote.ssh_url,
      preferredCloneUrl,
      updatedAt: remote.updated_at,
      localPath: local?.localPath || null,
      localStatus: status,
      linkState: local ? 'linked' : 'remote-only',
      deploymentProfiles: profiles,
      readyToDeploy,
      favorite: (this.store.data.favorites || []).includes(key),
      attention: conflict || behind > 0 || Boolean(local?.error),
      attentionReason: conflict ? 'Merge conflict' : behind > 0 ? `${behind} commit${behind === 1 ? '' : 's'} behind remote` : local?.error || null
    };
  }
}

module.exports = { RepositoryService, SKIP_DIRECTORIES, mapLimit };