import simpleGit, { SimpleGit, TaskOptions } from 'simple-git';
import * as path from 'path';
import * as fs from 'fs-extra';
import {
  AgentWorkspace,
  FileChange,
  WorkspaceChange,
  DiffResult,
  DiffFile,
  DiffLine,
  MergeResult,
  ConflictInfo
} from '../types/index';
import { GitAgentSyncError } from './errors';

export function createGit(basePath: string): SimpleGit {
  return simpleGit(basePath);
}

export async function getCurrentBranch(git: SimpleGit): Promise<string> {
  const { current } = await git.branch();
  if (!current) {
    throw new GitAgentSyncError('Could not determine current branch');
  }
  return current;
}

export async function getMainBranch(git: SimpleGit, defaultMain: string = 'main'): Promise<string> {
  const branches = await git.branch();
  if (branches.all.includes('main')) {
    return 'main';
  }
  if (branches.all.includes('master')) {
    return 'master';
  }
  return defaultMain;
}

export async function createWorktree(
  basePath: string,
  workspacePath: string,
  branchName: string,
  mainBranch: string
): Promise<void> {
  const git = createGit(basePath);

  await fs.ensureDir(workspacePath);

  try {
    await git.raw(['worktree', 'add', workspacePath, '-b', branchName]);
  } catch (error: any) {
    if (error.message?.includes('already exists')) {
      throw new GitAgentSyncError(`Worktree already exists at ${workspacePath}`);
    }
    throw new GitAgentSyncError(`Failed to create worktree: ${error.message}`);
  }
}

export async function removeWorktree(basePath: string, workspacePath: string, branchName: string): Promise<void> {
  const git = createGit(basePath);

  try {
    await git.raw(['worktree', 'remove', workspacePath, '--force']);
  } catch (error: any) {
    throw new GitAgentSyncError(`Failed to remove worktree: ${error.message}`);
  }
}

export async function deleteBranch(git: SimpleGit, branchName: string, force: boolean = false): Promise<void> {
  try {
    if (force) {
      await git.raw(['branch', '-D', branchName]);
    } else {
      await git.raw(['branch', '-d', branchName]);
    }
  } catch (error: any) {
    throw new GitAgentSyncError(`Failed to delete branch ${branchName}: ${error.message}`);
  }
}

export async function listWorktrees(basePath: string): Promise<{ path: string; branch: string }[]> {
  const git = createGit(basePath);
  const result = await git.raw(['worktree', 'list', '--porcelain']);

  const worktrees: { path: string; branch: string }[] = [];
  const lines = result.split('\n').filter(Boolean);

  for (const line of lines) {
    const match = line.match(/^worktree (.+)$/);
    if (match) {
      const worktreePath = match[1];
      const branchMatch = lines.find(l => l.startsWith(`branch ${worktreePath}`));
      if (branchMatch) {
        const branch = branchMatch.replace(/^branch\s+/, '');
        worktrees.push({ path: worktreePath, branch });
      }
    }
  }

  return worktrees;
}

export async function getWorktreeStatus(workspacePath: string): Promise<WorkspaceChange> {
  const git = createGit(workspacePath);

  const status = await git.status();
  const branch = await getCurrentBranch(git);
  const agentName = extractAgentName(branch);

  const changes: FileChange[] = [];

  for (const file of status.created) {
    changes.push({
      file,
      status: 'added',
      staged: true,
      author: 'agent',
      timestamp: new Date().toISOString(),
      diff: ''
    });
  }

  for (const file of status.modified) {
    const diff = await git.diff(['--no-color', file]);
    changes.push({
      file,
      status: 'modified',
      staged: status.staged.includes(file),
      author: 'agent',
      timestamp: new Date().toISOString(),
      diff
    });
  }

  for (const file of status.deleted) {
    changes.push({
      file,
      status: 'deleted',
      staged: status.staged.includes(file),
      author: 'agent',
      timestamp: new Date().toISOString(),
      diff: ''
    });
  }

  return {
    agentName,
    branch,
    path: workspacePath,
    changes,
    lastUpdated: new Date().toISOString(),
    uncommittedCount: status.modified.length + status.created.length + status.deleted.length
  };
}

export async function generateDiff(
  basePath: string,
  workspacePath: string,
  agentName: string,
  comparedBranch: string = 'main'
): Promise<DiffResult> {
  const git = createGit(workspacePath);
  const branch = await getCurrentBranch(git);

  const diffOutput = await git.diff(['--no-color', '--unified=3', comparedBranch]);

  const files = parseDiffOutput(diffOutput);
  const summary = calculateDiffSummary(files);

  return {
    agentName,
    branch,
    comparedBranch,
    files,
    summary
  };
}

export function parseDiffOutput(output: string): DiffFile[] {
  const files: DiffFile[] = [];
  const lines = output.split('\n');
  let currentFile: DiffFile | null = null;
  let currentChanges: DiffLine[] = [];
  let oldLineNum: number | null = null;
  let newLineNum: number | null = null;

  for (const line of lines) {
    const fileMatch = line.match(/^diff --git a\/(.+) b\/(.+)$/);
    if (fileMatch) {
      if (currentFile) {
        currentFile.changes = currentChanges;
        files.push(currentFile);
      }
      currentFile = {
        file: fileMatch[2] || fileMatch[1],
        oldFile: fileMatch[1] !== fileMatch[2] ? fileMatch[1] : undefined,
        changes: [],
        additions: 0,
        deletions: 0
      };
      currentChanges = [];
      oldLineNum = null;
      newLineNum = null;
      continue;
    }

    const indexMatch = line.match(/^index [a-f0-9]+\.[a-f0-9]+/);
    if (indexMatch && currentFile) {
      continue;
    }

    const newFileMatch = line.match(/^new file mode .+$/);
    if (newFileMatch && currentFile) {
      continue;
    }

    const oldFileMatch = line.match(/^deleted file mode .+$/);
    if (oldFileMatch && currentFile) {
      continue;
    }

    const hunkMatch = line.match(/^@@ -(\d+),?(\d*) \+(\d+),?(\d*) @@/);
    if (hunkMatch && currentFile) {
      oldLineNum = parseInt(hunkMatch[1], 10);
      newLineNum = parseInt(hunkMatch[3], 10);
      continue;
    }

    if (currentFile) {
      let lineType: 'context' | 'added' | 'deleted' = 'context';

      if (line.startsWith('+') && !line.startsWith('+++')) {
        lineType = 'added';
        currentFile.additions++;
      } else if (line.startsWith('-') && !line.startsWith('---')) {
        lineType = 'deleted';
        currentFile.deletions++;
      }

      currentChanges.push({
        type: lineType,
        lineNumber: {
          old: line.startsWith('+') || line.startsWith(' ') ? oldLineNum : null,
          new: line.startsWith('-') || line.startsWith(' ') ? newLineNum : null
        },
        content: line
      });

      if (lineType !== 'added' && line !== '') {
        oldLineNum = oldLineNum ? oldLineNum + 1 : null;
      }
      if (lineType !== 'deleted' && line !== '') {
        newLineNum = newLineNum ? newLineNum + 1 : null;
      }
    }
  }

  if (currentFile) {
    currentFile.changes = currentChanges;
    files.push(currentFile);
  }

  return files;
}

function calculateDiffSummary(files: DiffFile[]): { filesChanged: number; additions: number; deletions: number } {
  let additions = 0;
  let deletions = 0;

  for (const file of files) {
    additions += file.additions;
    deletions += file.deletions;
  }

  return {
    filesChanged: files.length,
    additions,
    deletions
  };
}

export async function mergeToMain(
  basePath: string,
  workspacePath: string,
  agentName: string,
  mainBranch: string,
  message?: string,
  dryRun: boolean = false
): Promise<MergeResult> {
  const git = createGit(workspacePath);
  const workspaceGit = createGit(workspacePath);
  const branch = await getCurrentBranch(workspaceGit);

  const commitMessage = message || `Merge agent-${agentName} changes into ${mainBranch}

Agent: ${agentName}
Branch: ${branch}
Date: ${new Date().toISOString()}

This commit was automatically generated by git-agent-sync`;

  if (dryRun) {
    return {
      success: true,
      message: `[DRY RUN] Would merge ${branch} into ${mainBranch}`,
      commitSha: 'dry-run'
    };
  }

  await workspaceGit.checkout(mainBranch);
  await workspaceGit.pull();

  try {
    const mergeResult = await git.raw([
      'merge',
      '--no-ff',
      '-m',
      commitMessage,
      branch
    ]);

    return {
      success: true,
      message: mergeResult,
      commitSha: ''
    };
  } catch (error: any) {
    if (error.message?.includes('conflict')) {
      const conflicts = await detectConflicts(workspacePath);
      return {
        success: false,
        conflicts,
        error: 'Merge conflicts detected'
      };
    }
    throw new GitAgentSyncError(`Merge failed: ${error.message}`);
  }
}

async function detectConflicts(workspacePath: string): Promise<ConflictInfo[]> {
  const git = createGit(workspacePath);
  const status = await git.status();

  const conflicts: ConflictInfo[] = [];

  for (const file of status.conflicted) {
    const content = await fs.readFile(path.join(workspacePath, file), 'utf-8');
    conflicts.push({
      file,
      content
    });
  }

  return conflicts;
}

export async function hasUncommittedChanges(workspacePath: string): Promise<boolean> {
  const git = createGit(workspacePath);
  const status = await git.status();
  return status.modified.length > 0 ||
    status.created.length > 0 ||
    status.deleted.length > 0;
}

export async function getLastCommitInfo(workspacePath: string): Promise<{ hash: string; message: string }> {
  const git = createGit(workspacePath);
  const log = await git.log({ maxCount: 1 });

  if (log.latest) {
    return {
      hash: log.latest.hash,
      message: log.latest.message || ''
    };
  }

  return {
    hash: '',
    message: ''
  };
}

export function extractAgentName(branch: string): string {
  return branch.replace(/^agent-/, '');
}

export async function stashChanges(workspacePath: string, message: string): Promise<void> {
  const git = createGit(workspacePath);
  await git.stash(['push', '-m', message]);
}

export async function applyStash(workspacePath: string, stashRef: string): Promise<void> {
  const git = createGit(workspacePath);
  await git.stash(['apply', stashRef]);
}

export async function getStashList(workspacePath: string): Promise<{ hash: string; message: string }[]> {
  const git = createGit(workspacePath);
  const stashList = await git.stash(['list']);

  const stashes: { hash: string; message: string }[] = [];
  const lines = stashList.split('\n').filter(Boolean);

  for (const line of lines) {
    const match = line.match(/^(\w+@.+): (.+)$/);
    if (match) {
      stashes.push({
        hash: match[1],
        message: match[2]
      });
    }
  }

  return stashes;
}

export async function exportChangesAsPatch(workspacePath: string, outputPath: string): Promise<void> {
  const git = createGit(workspacePath);
  const diff = await git.diff(['--no-color', '--unified=3']);

  await fs.writeFile(outputPath, diff, 'utf-8');
}