import { createRequire } from "node:module";
import { isAbsolute, join } from "node:path";
import { $inject, Alepha, AlephaError } from "alepha";
import { $logger } from "alepha/logger";
import { FileSystemProvider } from "alepha/system";
import type * as vite from "vite";
import type { UserConfig } from "vite";
import { analyzer as viteAnalyzer } from "vite-bundle-analyzer";
import { ViteUtils } from "../services/ViteUtils.ts";
import { BuildTask, type BuildTaskContext } from "./BuildTask.ts";

/**
 * Build server-side SSR bundle with Vite.
 *
 * Compiles the server code for production, generates the externals
 * package.json, and creates the dist/index.js entry wrapper.
 */
export class BuildServerTask extends BuildTask {
  protected readonly alepha = $inject(Alepha);
  protected readonly log = $logger();
  protected readonly fs = $inject(FileSystemProvider);
  protected readonly viteUtils = $inject(ViteUtils);

  async run(ctx: BuildTaskContext): Promise<void> {
    if (ctx.flags?.prebuilt) {
      return;
    }
    const distDir = ctx.options.output?.dist ?? "dist";
    const publicDir = ctx.options.output?.public ?? "public";
    const stats = ctx.options.stats ?? false;
    const isCI = this.alepha.isCI();

    const clientIndexPath = this.fs.join(
      ctx.root,
      distDir,
      publicDir,
      "index.html",
    );
    const clientBuilt = await this.fs.exists(clientIndexPath);

    const conditions: string[] = [];
    if (ctx.options.runtime === "bun") {
      conditions.push("bun");
    } else if (ctx.options.runtime === "workerd") {
      conditions.push("workerd");
    }

    await ctx.run({
      name: "build server",
      handler: async () => {
        await this.buildServer({
          root: ctx.root,
          entry: ctx.entry.server,
          distDir,
          clientDir: clientBuilt ? publicDir : undefined,
          stats,
          silent: !isCI,
          conditions,
          alepha: ctx.alepha,
        });

        // Server will handle index.html if both client & server are built
        if (clientBuilt) {
          await this.fs.rm(clientIndexPath);
        }
      },
    });
  }

  protected async buildServer(opts: {
    root: string;
    entry: string;
    distDir: string;
    clientDir?: string;
    stats?: boolean | "json";
    silent?: boolean;
    conditions?: string[];
    alepha: Alepha;
  }): Promise<void> {
    const { build: viteBuild, resolveConfig } =
      await this.viteUtils.importVite();
    const plugins: any[] = [];

    const viteReact = await this.viteUtils.importViteReact();
    if (viteReact && opts.clientDir) {
      plugins.push(viteReact());
    }

    plugins.push(this.viteUtils.createTsconfigPathsPlugin());
    plugins.push(this.viteUtils.createSsrPreloadPlugin());

    if (opts.stats) {
      plugins.push(
        viteAnalyzer({
          analyzerMode: opts.stats === "json" ? "json" : "static",
        }),
      );
    }

    const logger = opts.silent
      ? this.viteUtils.createBufferedLogger()
      : undefined;

    const conditions = ["node", "import", "module", "default"];
    if (opts.conditions) {
      conditions.unshift(...opts.conditions);
    }

    const viteBuildServerConfig: UserConfig = {
      mode: "production",
      logLevel: opts.silent ? "silent" : undefined,
      define: {
        "process.env.NODE_ENV": '"production"',
      },
      resolve: {
        dedupe: [
          "react",
          "react-dom",
          "react/jsx-runtime",
          "react/jsx-dev-runtime",
        ],
      },
      publicDir: false,
      ssr: {
        noExternal: true,
        resolve: { conditions },
      },
      build: {
        ssr: opts.entry,
        minify: true,
        sourcemap: true,
        chunkSizeWarningLimit: 10000,
        outDir: `${opts.distDir}/server`,
        rolldownOptions: {
          external: [/^bun(:|$)/, /^cloudflare:/],
          output: {
            entryFileNames: "[hash].js",
            chunkFileNames: "[hash].js",
            assetFileNames: "[hash][extname]",
            format: "esm",
            codeSplitting: {
              groups: [
                {
                  name: "react",
                  test: /node_modules\/react(\/|-dom\/)/,
                },
              ],
            },
            // Rolldown/Oxc minifier: preserve class and function names
            minify: {
              mangle: { keepNames: true },
              compress: {
                keepNames: { function: true, class: true },
              },
            },
          },
        },
      },
      customLogger: logger,
      plugins,
    };

    let result: vite.Rollup.RollupOutput | vite.Rollup.RollupOutput[];
    try {
      result = (await viteBuild(viteBuildServerConfig)) as
        | vite.Rollup.RollupOutput
        | vite.Rollup.RollupOutput[];
    } catch (error) {
      logger?.flush();
      throw error;
    }

    const resolvedConfig = await resolveConfig(viteBuildServerConfig, "build");

    const externals: string[] = [];
    if (Array.isArray(resolvedConfig?.ssr?.external)) {
      externals.push(...resolvedConfig.ssr.external);
    }

    await this.generateExternals(opts.distDir, externals);

    const entryFile = this.extractEntryFromBundle(
      opts.root,
      opts.entry,
      result,
    );

    let manifest = "";
    let manifestData:
      | {
          base?: string;
          client?: Record<string, any>;
          preload?: Record<string, string>;
          favicon?: string;
        }
      | undefined;

    if (opts.clientDir) {
      const viteDir = `${opts.distDir}/${opts.clientDir}/.vite`;
      const clientManifest = await this.loadJsonFile(
        `${viteDir}/manifest.json`,
      );
      const preloadManifest = await this.loadJsonFile(
        `${viteDir}/preload-manifest.json`,
      );

      const strippedClientManifest = this.stripClientManifest(clientManifest);

      let base = resolvedConfig.base || "/";
      if (!base.startsWith("/")) {
        base = `/${base}`;
      }
      if (base.length > 1 && base.endsWith("/")) {
        base = base.slice(0, -1);
      }

      const favicon = await this.detectFavicon(
        `${opts.distDir}/${opts.clientDir}`,
      );

      manifestData = {
        base: base !== "/" ? base : undefined,
        client: strippedClientManifest,
        preload: preloadManifest,
        favicon,
      };

      manifest = `__alepha.set("alepha.react.ssr.manifest", ${JSON.stringify(manifestData, null, "  ")});\n`;

      opts.alepha.store.set("alepha.react.ssr.manifest" as any, manifestData);

      await this.fs.rm(viteDir, { recursive: true });
    }

    const warning =
      "// This file was automatically generated. DO NOT MODIFY." +
      "\n" +
      "// Changes to this file will be lost when the code is regenerated.\n";

    await this.fs.writeFile(
      `${opts.distDir}/index.js`,
      `${warning}\nimport './server/${entryFile}';\n\n${manifest}`.trim(),
    );
  }

  /**
   * Detect a favicon file in the given directory.
   * Returns "mimeType:/path" if found, undefined otherwise.
   */
  protected async detectFavicon(
    publicDir: string,
  ): Promise<string | undefined> {
    const candidates: [string, string][] = [
      ["favicon.svg", "image/svg+xml"],
      ["favicon.png", "image/png"],
      ["favicon.ico", "image/x-icon"],
    ];
    for (const [file, mime] of candidates) {
      if (await this.fs.exists(join(publicDir, file))) {
        return `${mime}:/${file}`;
      }
    }
    return undefined;
  }

  protected async generateExternals(
    distDir: string,
    externals: string[],
  ): Promise<void> {
    const require = createRequire(import.meta.filename);
    const deps: Record<string, string> = {};

    for (const dep of externals) {
      try {
        const requirePath = require.resolve(dep);
        const pkgPath = `${requirePath.split(`node_modules/${dep}`)[0]}node_modules/${dep}/package.json`;
        const pkg = JSON.parse((await this.fs.readFile(pkgPath)).toString());
        deps[dep] = `^${pkg.version}`;
      } catch {
        this.log.warn(`Cannot find '${dep}' in node_modules`);
      }
    }

    const minimalPkg = {
      type: "module",
      main: "index.js",
      dependencies: deps,
    };

    await this.fs.mkdir(distDir);
    await this.fs.writeFile(
      join(distDir, "package.json"),
      JSON.stringify(minimalPkg, null, 2),
    );
  }

  protected async loadJsonFile(path: string): Promise<any> {
    try {
      const content = (await this.fs.readFile(path)).toString();
      return JSON.parse(content);
    } catch {
      return undefined;
    }
  }

  protected stripClientManifest(
    manifest: Record<string, any> | undefined,
  ): Record<string, any> | undefined {
    if (!manifest) return undefined;

    const stripped: Record<string, any> = {};
    for (const [key, entry] of Object.entries(manifest)) {
      stripped[key] = {
        file: entry.file,
        ...(entry.isEntry && { isEntry: entry.isEntry }),
        ...(entry.imports?.length && { imports: entry.imports }),
        ...(entry.css?.length && { css: entry.css }),
      };
    }
    return stripped;
  }

  protected extractEntryFromBundle(
    root: string,
    entry: string,
    result:
      | vite.Rollup.RollupOutput
      | vite.Rollup.RollupOutput[]
      | vite.Rollup.RollupWatcher,
  ): string {
    const entryFilePath = isAbsolute(entry) ? entry : join(root, entry);

    const normalizedEntryPath = entryFilePath.replace(/\\/g, "/");

    const rollupOutput = (
      Array.isArray(result) ? result[0] : result
    ) as vite.Rollup.RollupOutput;

    const entryFile = rollupOutput.output.find(
      (it) =>
        "facadeModuleId" in it && it.facadeModuleId === normalizedEntryPath,
    )?.fileName;

    if (!entryFile) {
      throw new AlephaError(
        `Could not find the entry file "${entryFilePath}" in the build output. Please check your entry file and try again.`,
      );
    }

    return entryFile;
  }
}