import type { GitChangeContext, GitCommitResult } from "../types.ts";

import { collectRepositoryFingerprint } from "./collect-changes.ts";
import { GitClient } from "./git-client.ts";

/** 提交前只重新计算轻量指纹，并确认生成依据没有发生变化。 */
async function assertRepositoryUnchanged(
  git: GitClient,
  original: GitChangeContext,
  signal?: AbortSignal,
): Promise<void> {
  const latest = await collectRepositoryFingerprint(
    git,
    original.root,
    original.requestedSource,
    signal,
  );
  if (
    latest.resolvedSource !== original.resolvedSource ||
    latest.fingerprint !== original.fingerprint
  ) {
    throw new Error(
      "The repository changed after the commit message was generated. To avoid committing unreviewed changes, the commit was cancelled. Please regenerate the message.",
    );
  }
}

/** 确保暂存区确实包含可提交变化。 */
async function assertIndexHasChanges(
  git: GitClient,
  root: string,
  signal?: AbortSignal,
): Promise<void> {
  const result = await git.run(["diff", "--cached", "--quiet", "--exit-code", "--"], {
    cwd: root,
    signal,
    acceptedExitCodes: [0, 1],
  });
  if (result.code === 0) {
    throw new Error("The staging area has no changes to commit.");
  }
}

/** 校验待提交消息的基本 Git 兼容性。 */
function validateCommitMessage(message: string): string {
  const normalized = message.trim();
  if (!normalized) {
    throw new Error("The commit message must not be empty.");
  }
  if (normalized.includes("\0")) {
    throw new Error("The commit message must not contain NUL characters.");
  }
  return normalized;
}

/** 在用户确认后安全地暂存所需内容并创建本地提交。 */
export async function createGitCommit(
  git: GitClient,
  original: GitChangeContext,
  message: string,
  options?: { signoff?: boolean; signal?: AbortSignal },
): Promise<GitCommitResult> {
  const signal = options?.signal;
  const normalizedMessage = validateCommitMessage(message);
  await assertRepositoryUnchanged(git, original, signal);

  let stagedByExtension = false;
  if (original.resolvedSource === "all") {
    await git.run(["add", "-A", "--", "."], {
      cwd: original.root,
      signal,
      timeout: 30_000,
    });
    stagedByExtension = true;
  }

  await assertIndexHasChanges(git, original.root, signal);

  const commitArgs = ["commit", "--message", normalizedMessage];
  if (options?.signoff) {
    commitArgs.push("--signoff");
  }

  let commitResult;
  try {
    commitResult = await git.run(commitArgs, {
      cwd: original.root,
      signal,
      timeout: 120_000,
    });
  } catch (error) {
    if (stagedByExtension) {
      const detail = error instanceof Error ? error.message : String(error);
      throw new Error(
        `${detail} The extension staged changes in all mode, but the commit failed. The staged state was preserved to avoid altering your work.`,
      );
    }
    throw error;
  }

  const hashResult = await git.run(["rev-parse", "--short", "HEAD"], {
    cwd: original.root,
    signal,
  });
  return {
    hash: hashResult.stdout.trim(),
    output: commitResult.stdout.trim(),
  };
}