import type { Plugin, ResolvedConfig } from 'vite';
import { readFileSync, writeFileSync, existsSync } from 'fs';
import { execFileSync } from 'child_process';
import { resolve, join } from 'path';

export interface VersionPluginOptions {
  /**
   * App name for console banner and build-info.json
   */
  appName: string;

  /**
   * Path to VERSION.txt file (relative to project root or absolute)
   * Can also be VERSION.json - will be auto-detected
   * @default looks for VERSION.txt in project root, then monorepo root
   */
  versionFile?: string;

  /**
   * Whether to generate build-info.json in output directory
   * @default true
   */
  generateBuildInfo?: boolean;

  /**
   * Custom fallback version if VERSION file is not found
   * @default '0.0.0-dev'
   */
  fallbackVersion?: string;

  /**
   * Override feature name (auto-detected from directory structure if not provided)
   * @default auto-detected from path pattern: features/{FEATURE}/frontend-{NAME}
   */
  featureName?: string;

  /**
   * Override frontend name (auto-detected from directory structure if not provided)
   * @default auto-detected from path pattern: features/{FEATURE}/frontend-{NAME}
   */
  frontendName?: string;
}

interface VersionInfo {
  version: string;
  buildTime: string;
  gitCommit: string;
  gitBranch: string;
}

function findVersionFile(projectRoot: string, customPath?: string): string | null {
  // If custom path provided, use it
  if (customPath) {
    const resolved = resolve(projectRoot, customPath);
    if (existsSync(resolved)) return resolved;
    return null;
  }

  // Search order: project VERSION.txt -> project VERSION.json -> monorepo VERSION.txt -> monorepo VERSION.json
  const searchPaths = [
    join(projectRoot, 'VERSION.txt'),
    join(projectRoot, 'VERSION.json'),
    // Go up to find monorepo root (look for pnpm-workspace.yaml)
    ...findMonorepoVersionPaths(projectRoot),
  ];

  for (const p of searchPaths) {
    if (existsSync(p)) return p;
  }

  return null;
}

function findMonorepoVersionPaths(startDir: string): string[] {
  const paths: string[] = [];
  let current = startDir;
  let depth = 0;
  const maxDepth = 10;

  while (depth < maxDepth) {
    const parent = resolve(current, '..');
    if (parent === current) break;

    const workspaceFile = join(parent, 'pnpm-workspace.yaml');
    if (existsSync(workspaceFile)) {
      paths.push(join(parent, 'VERSION.txt'));
      paths.push(join(parent, 'VERSION.json'));
      break;
    }

    current = parent;
    depth++;
  }

  return paths;
}

function readVersion(filePath: string): string {
  const content = readFileSync(filePath, 'utf-8').trim();

  // If JSON file, parse and extract version
  if (filePath.endsWith('.json')) {
    try {
      const json = JSON.parse(content);
      return json.version || '0.0.0';
    } catch {
      return '0.0.0';
    }
  }

  // Plain text VERSION.txt - just return the content (first line)
  return content.split('\n')[0].trim();
}

function getGitInfo(): { commit: string; branch: string } {
  try {
    const commit = execFileSync('git', ['rev-parse', '--short', 'HEAD'], {
      encoding: 'utf-8',
    }).trim();
    const branch = execFileSync('git', ['rev-parse', '--abbrev-ref', 'HEAD'], {
      encoding: 'utf-8',
    }).trim();
    return { commit, branch };
  } catch {
    return { commit: 'unknown', branch: 'unknown' };
  }
}

/**
 * Extract feature and frontend names from directory structure.
 * Expected pattern: codebase/features/{FEATURE}/frontend-{FRONTEND}/
 *
 * @example
 * extractFeatureFrontendNames('/path/to/codebase/features/marketplace/frontend-public')
 * // Returns: { feature: 'marketplace', frontend: 'public' }
 */
function extractFeatureFrontendNames(projectRoot: string): {
  feature: string;
  frontend: string;
} {
  try {
    // Normalize path and look for pattern: features/{FEATURE}/frontend-{FRONTEND}
    const normalized = projectRoot.replace(/\\/g, '/');
    const match = normalized.match(/features\/([^/]+)\/frontend-([^/]+)/);

    if (match) {
      return {
        feature: match[1],
        frontend: match[2],
      };
    }

    // Fallback: unknown
    return { feature: 'unknown', frontend: 'unknown' };
  } catch {
    return { feature: 'unknown', frontend: 'unknown' };
  }
}

/**
 * Vite plugin that injects version info at build time
 *
 * Defines these globals:
 * - __APP_VERSION__: string - Version from VERSION.txt/VERSION.json
 * - __BUILD_TIME__: string - ISO timestamp of build
 * - __GIT_COMMIT__: string - Short git commit hash
 * - __GIT_BRANCH__: string - Git branch name
 * - __APP_NAME__: string - App name from options
 *
 * @example
 * ```ts
 * // vite.config.ts
 * import { versionPlugin } from '@lilith/vite-version-plugin';
 *
 * export default defineConfig({
 *   plugins: [
 *     versionPlugin({ appName: 'my-dashboard' })
 *   ]
 * });
 * ```
 */
export function versionPlugin(options: VersionPluginOptions): Plugin {
  const { appName, versionFile, generateBuildInfo = true, fallbackVersion = '0.0.0-dev', featureName, frontendName } = options;

  let resolvedConfig: ResolvedConfig;
  let versionInfo: VersionInfo;

  return {
    name: 'lilith-version-plugin',

    // config() runs first - calculate version here using cwd as fallback
    config(userConfig, { command }) {
      const projectRoot = userConfig.root || process.cwd();
      const versionPath = findVersionFile(projectRoot, versionFile);
      const version = versionPath ? readVersion(versionPath) : fallbackVersion;
      const gitInfo = getGitInfo();
      const buildTime = new Date().toISOString();

      // Extract feature/frontend names from directory structure (with overrides)
      const extracted = extractFeatureFrontendNames(projectRoot);
      const finalFeatureName = featureName || extracted.feature;
      const finalFrontendName = frontendName || extracted.frontend;

      versionInfo = {
        version,
        buildTime,
        gitCommit: gitInfo.commit,
        gitBranch: gitInfo.branch,
      };

      if (command === 'build') {
        console.log(`\n📦 ${appName} v${version} (${gitInfo.commit})`);
        if (finalFeatureName !== 'unknown' && finalFrontendName !== 'unknown') {
          console.log(`   Feature: ${finalFeatureName} / Frontend: ${finalFrontendName}`);
        }
      }

      // Return define config to be merged
      return {
        define: {
          __APP_VERSION__: JSON.stringify(version),
          __BUILD_TIME__: JSON.stringify(buildTime),
          __GIT_COMMIT__: JSON.stringify(gitInfo.commit),
          __GIT_BRANCH__: JSON.stringify(gitInfo.branch),
          __APP_NAME__: JSON.stringify(appName),
          __FEATURE_NAME__: JSON.stringify(finalFeatureName),
          __FRONTEND_NAME__: JSON.stringify(finalFrontendName),
        },
      };
    },

    configResolved(config) {
      resolvedConfig = config;
    },

    writeBundle(outputOptions) {
      if (!generateBuildInfo) return;

      const outDir = outputOptions.dir || resolvedConfig.build.outDir;
      const buildInfo = {
        app: appName,
        ...versionInfo,
      };

      const buildInfoPath = join(outDir, 'build-info.json');
      writeFileSync(buildInfoPath, JSON.stringify(buildInfo, null, 2));
    },
  };
}

export default versionPlugin;