import MagicString from 'magic-string';
import { URL, URLSearchParams } from 'node:url';
import path from 'node:path';
import fs from 'node:fs/promises';
import { createHash } from 'node:crypto';
import type { Plugin, InlineConfig, Rolldown } from 'vite';
import { build as viteBuild, mergeConfig } from 'vite';

function toRelativePath(filename: string, importer: string): string {
  const relPath = path.posix.relative(path.dirname(importer), filename);
  return relPath.startsWith('.') ? relPath : `./${relPath}`;
}

function parseRequest(id: string): Record<string, string> | null {
  try {
    const { search } = new URL(id, 'file:');
    if (!search) {
      return null;
    }
    return Object.fromEntries(new URLSearchParams(search));
  } catch {
    return null;
  }
}

function getHash(text: string): string {
  return createHash('sha256').update(text).digest('hex').substring(0, 8);
}

const queryRE = /\?.*$/s;
const hashRE = /#.*$/s;
const cleanUrl = (url: string): string =>
  url.replace(hashRE, '').replace(queryRE, '');

const modulePathRE = /__VITE_MODULE_PATH__([\w$]+)__/g;

// ESM shim for __dirname
const CJSShim = `
import __cjs_url__ from 'node:url';
import __cjs_path__ from 'node:path';
const __filename = __cjs_url__.fileURLToPath(import.meta.url);
const __dirname = __cjs_path__.dirname(__filename);
`;

interface ModulePathPluginOptions {
  /**
   * Vite configuration to use for bundling modules
   */
  bundleConfig?: InlineConfig;
}

interface EmittedChunk {
  fileName: string;
  code: string;
  referenceId: string;
}

/**
 * Resolve `?modulePath` import and return the module bundle path.
 */
export default function modulePathPlugin(
  options: ModulePathPluginOptions = {}
): Plugin {
  let sourcemap = false;
  let viteConfig: InlineConfig;
  let rootDir: string;
  let outDir: string;
  let isDev = false;
  const assetCache = new Map<string, string>(); // original path -> hashed fileName
  const chunksToWrite = new Map<string, EmittedChunk>(); // fileName -> chunk data
  const chunkShims = new Set<string>();
  const fileNameMap = new Map<string, string>(); // original fileName -> hashed fileName

  return {
    name: 'vite:module-path',
    enforce: 'pre',

    configResolved(config) {
      isDev = config.command === 'serve';
      sourcemap = !!config.build.sourcemap;
      rootDir = config.root;
      outDir = path.resolve(rootDir, config.build.outDir);

      if (!isDev) {
        viteConfig = {
          root: config.root,
          mode: config.mode,
          configFile: false,
          logLevel: 'warn',
          ...options.bundleConfig,
          build: {
            ...options.bundleConfig?.build,
            write: false,
            lib: undefined,
            rollupOptions: {
              ...options.bundleConfig?.build?.rollupOptions,
              output: {
                format: 'es',
                entryFileNames: '[name].js',
                chunkFileNames: '[name]-[hash].js',
                assetFileNames: '[name]-[hash][extname]',
                ...(options.bundleConfig?.build?.rollupOptions?.output as any),
              },
            },
          },
        };

        console.log(`[module-path] Output directory: ${outDir}`);
      }
    },

    buildStart() {
      if (!isDev) {
        assetCache.clear();
        chunksToWrite.clear();
        chunkShims.clear();
        fileNameMap.clear();
      }
    },

    async resolveId(id, importer) {
      const query = parseRequest(id);
      if (query && typeof query.modulePath === 'string') {
        // dev 모드에서는 절대 경로로 변환
        if (isDev) {
          const cleanPath = cleanUrl(id);

          // 절대 경로가 아니면 importer 기준으로 resolve
          let resolvedPath: string;
          if (path.isAbsolute(cleanPath)) {
            resolvedPath = cleanPath;
          } else if (importer) {
            resolvedPath = path.resolve(path.dirname(importer), cleanPath);
          } else {
            resolvedPath = path.resolve(rootDir, cleanPath);
          }

          console.log(`[module-path] Resolved: ${id} -> ${resolvedPath}`);

          // 절대 경로에 플래그 추가
          return resolvedPath + '?__modulePath__=true';
        }
      }
      return null;
    },

    async load(id) {
      const query = parseRequest(id);

      // Dev 모드: 파일을 실행하지 않고 경로만 반환
      if (isDev && query && query.__modulePath__ === 'true') {
        const cleanPath = cleanUrl(id);
        console.log(
          `[module-path] Dev mode: returning file path for ${cleanPath}`
        );

        // 절대 경로를 그대로 반환 (dev 모드에서는 소스 파일 직접 사용)
        return `export default ${JSON.stringify(cleanPath)}`;
      }

      // Build 모드: 번들링 수행
      if (!isDev && query && typeof query.modulePath === 'string') {
        const cleanPath = cleanUrl(id);

        // 이미 처리된 파일인지 확인
        if (assetCache.has(cleanPath)) {
          const hashedFileName = assetCache.get(cleanPath)!;
          const referenceId = chunksToWrite.get(hashedFileName)?.referenceId;

          if (referenceId) {
            console.log(
              `[module-path] Reusing cached bundle: ${cleanPath} -> ${hashedFileName}`
            );
            const refId = `__VITE_MODULE_PATH__${referenceId}__`;

            return `
import { fileURLToPath } from 'node:url'
import { dirname, join } from 'node:path'
const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)
export default join(__dirname, ${refId})`;
          }
        }

        console.log(`[module-path] Bundling module: ${cleanPath}`);

        try {
          const { outputChunks } = await bundleModule(cleanPath, viteConfig);

          if (outputChunks.length === 0) {
            throw new Error(`No output chunks generated for: ${cleanPath}`);
          }

          console.log(
            `[module-path] Generated ${outputChunks.length} chunk(s)`
          );

          // 메인 청크에 대해 고유한 파일명 생성
          const mainChunk = outputChunks[0];
          const mainChunkHash = getHash(cleanPath + mainChunk.code);
          const ext = path.extname(mainChunk.fileName);
          const baseName = path.basename(mainChunk.fileName, ext);
          const hashedMainFileName = `${baseName}-${mainChunkHash}${ext}`;

          // 파일명 매핑 저장
          fileNameMap.set(mainChunk.fileName, hashedMainFileName);

          console.log(
            `[module-path] Main chunk: ${mainChunk.fileName} -> ${hashedMainFileName}`
          );

          let mainReferenceId: string | undefined;

          // 모든 청크를 저장
          for (const chunk of outputChunks) {
            const originalFileName = chunk.fileName;
            const isMainChunk = chunk === mainChunk;

            // 메인 청크는 이미 해시된 이름 사용, 나머지는 원본 이름 또는 이미 해시된 이름 사용
            const fileName = isMainChunk
              ? hashedMainFileName
              : fileNameMap.get(originalFileName) || originalFileName;

            // 동일한 파일이 이미 처리되었는지 확인
            if (chunksToWrite.has(fileName)) {
              console.log(`[module-path] Skipping duplicate: ${fileName}`);
              if (isMainChunk) {
                mainReferenceId = chunksToWrite.get(fileName)!.referenceId;
              }
              continue;
            }

            // 청크의 import 경로를 수정 (다른 청크를 참조하는 경우)
            let code =
              chunk.type === 'chunk' ? chunk.code : (chunk.source as string);

            if (chunk.type === 'chunk') {
              // import 문에서 다른 청크를 참조하는 경우 해시된 이름으로 변경
              for (const [original, hashed] of fileNameMap) {
                if (original !== hashed) {
                  const importRegex = new RegExp(
                    `(from\\s+['"]\\.\\/)(${original.replace('.', '\\.')})(['"])`,
                    'g'
                  );
                  code = code.replace(importRegex, `$1${hashed}$3`);
                }
              }
            }

            // emitFile로 참조 ID 생성
            const referenceId = this.emitFile({
              type: 'asset',
              fileName: fileName,
              source: code,
            });

            if (isMainChunk) {
              mainReferenceId = referenceId;
              assetCache.set(cleanPath, fileName);
            }

            // 나중에 직접 쓰기 위해 저장
            chunksToWrite.set(fileName, {
              fileName,
              code,
              referenceId,
            });

            if (chunk.type === 'chunk') {
              chunkShims.add(fileName);
            }

            console.log(`[module-path] Processed: ${fileName}`);
          }

          if (!mainReferenceId) {
            throw new Error('Failed to process main chunk');
          }

          const refId = `__VITE_MODULE_PATH__${mainReferenceId}__`;

          return `
import { fileURLToPath } from 'node:url'
import { dirname, join } from 'node:path'
const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)
export default join(__dirname, ${refId})`;
        } catch (error) {
          console.error(`[module-path] Bundle error:`, error);
          throw error;
        }
      }
    },

    renderChunk(code, chunk) {
      if (isDev) return null;

      let modified = false;
      let s: MagicString | undefined;

      if (code.match(modulePathRE)) {
        s = new MagicString(code);
        let match: RegExpExecArray | null;

        modulePathRE.lastIndex = 0;
        while ((match = modulePathRE.exec(code))) {
          const [full, hash] = match;
          const filename = this.getFileName(hash);
          const outputFilepath = toRelativePath(filename, chunk.fileName);
          const replacement = JSON.stringify(outputFilepath);
          s.overwrite(match.index, match.index + full.length, replacement, {
            contentOnly: true,
          });
          modified = true;
        }
      }

      if (chunkShims.has(chunk.fileName) && !code.includes('const __dirname')) {
        s = s || new MagicString(code);

        const importMatches = Array.from(
          code.matchAll(/import\s+.*?from\s+['"][^'"]+['"]\s*;?/g)
        );
        const lastImport = importMatches[importMatches.length - 1];
        const insertPos = lastImport
          ? lastImport.index! + lastImport[0].length
          : 0;

        s.appendRight(insertPos, CJSShim);
        modified = true;
      }

      if (modified && s) {
        return {
          code: s.toString(),
          map: sourcemap ? s.generateMap({ hires: 'boundary' }) : null,
        };
      }

      return null;
    },

    async writeBundle(options, bundle) {
      if (isDev) return;

      console.log(
        `[module-path] Writing ${chunksToWrite.size} additional chunk(s)`
      );

      for (const [fileName, chunkData] of chunksToWrite) {
        const outputPath = path.resolve(outDir, fileName);

        try {
          await fs.mkdir(path.dirname(outputPath), { recursive: true });
          await fs.writeFile(outputPath, chunkData.code, 'utf-8');

          console.log(`[module-path] Written: ${fileName}`);
        } catch (error) {
          console.error(`[module-path] Failed to write ${fileName}:`, error);
          throw error;
        }
      }

      console.log(`[module-path] All chunks written successfully`);
    },
  };
}

async function bundleModule(
  input: string,
  baseConfig: InlineConfig
): Promise<{ outputChunks: any[] }> {
  const entryName = path.basename(input, path.extname(input));

  const buildConfig = mergeConfig(baseConfig, {
    build: {
      write: false,
      emptyOutDir: false,
      rollupOptions: {
        input: {
          [entryName]: input,
        },
        preserveEntrySignatures: 'strict',
      },
    },
  }) as InlineConfig;

  try {
    const bundles = (await viteBuild(buildConfig)) as Rolldown.RolldownOutput;

    if (!bundles || !bundles.output) {
      throw new Error('No output from vite build');
    }

    const outputChunks = bundles.output;

    return { outputChunks };
  } catch (error) {
    console.error('[module-path] Bundle error:', error);
    throw error;
  }
}