import * as fs from 'fs-extra';
import * as path from 'path';
import { DiffResult, DiffFile, DiffLine, FileChange } from '../types/index';
export { parseDiffOutput } from './git-utils';

export function formatDiffAsMarkdown(diffResult: DiffResult): string {
  const lines: string[] = [];

  lines.push(`# Agent Changes: ${diffResult.agentName}`);
  lines.push('');
  lines.push(`**Branch:** \`${diffResult.branch}\``);
  lines.push(`**Compared to:** \`${diffResult.comparedBranch}\``);
  lines.push(`**Files Changed:** ${diffResult.summary.filesChanged}`);
  lines.push(`**Additions:** \`+${diffResult.summary.additions}\``);
  lines.push(`**Deletions:** \`-${diffResult.summary.deletions}\``);
  lines.push('');
  lines.push('---');
  lines.push('');

  for (const file of diffResult.files) {
    lines.push(`## ${file.file}`);
    lines.push('');
    lines.push('```diff');

    for (const line of file.changes) {
      lines.push(line.content);
    }

    lines.push('```');
    lines.push('');
  }

  return lines.join('\n');
}

export function formatDiffAsJson(diffResult: DiffResult): string {
  return JSON.stringify(diffResult, null, 2);
}

export function formatDiffAsText(diffResult: DiffResult): string {
  const lines: string[] = [];

  lines.push(`Agent: ${diffResult.agentName}`);
  lines.push(`Branch: ${diffResult.branch}`);
  lines.push(`Compared to: ${diffResult.comparedBranch}`);
  lines.push(`Files Changed: ${diffResult.summary.filesChanged}`);
  lines.push(`Additions: +${diffResult.summary.additions}`);
  lines.push(`Deletions: -${diffResult.summary.deletions}`);
  lines.push('');
  lines.push('---');
  lines.push('');

  for (const file of diffResult.files) {
    lines.push(`File: ${file.file}`);
    for (const line of file.changes) {
      if (line.type !== 'context') {
        lines.push(`  ${line.content}`);
      }
    }
    lines.push('');
  }

  return lines.join('\n');
}

export function formatChangesForReview(
  workspacePath: string,
  changes: FileChange[],
  agentName: string
): string {
  const lines: string[] = [];

  lines.push(`# Code Review: Agent ${agentName}`);
  lines.push('');
  lines.push(`**Date:** ${new Date().toISOString()}`);
  lines.push(`**Workspace:** ${workspacePath}`);
  lines.push('');
  lines.push('## Summary');
  lines.push('');
  const added = changes.filter(c => c.status === 'added').length;
  const modified = changes.filter(c => c.status === 'modified').length;
  const deleted = changes.filter(c => c.status === 'deleted').length;
  lines.push(`- Added: ${added}`);
  lines.push(`- Modified: ${modified}`);
  lines.push(`- Deleted: ${deleted}`);
  lines.push('');
  lines.push('## Changes');
  lines.push('');

  for (const change of changes) {
    lines.push(`### ${change.file} (\`${change.status}\`)`);
    lines.push('');

    if (change.diff) {
      lines.push('```diff');
      lines.push(change.diff);
      lines.push('```');
    }

    lines.push('');
  }

  return lines.join('\n');
}

export async function exportDiffToFile(
  diffResult: DiffResult,
  outputPath: string,
  format: 'markdown' | 'json' | 'text' = 'markdown'
): Promise<void> {
  let content: string;

  switch (format) {
    case 'markdown':
      content = formatDiffAsMarkdown(diffResult);
      break;
    case 'json':
      content = formatDiffAsJson(diffResult);
      break;
    case 'text':
      content = formatDiffAsText(diffResult);
      break;
    default:
      content = formatDiffAsMarkdown(diffResult);
  }

  await fs.ensureDir(path.dirname(outputPath));
  await fs.writeFile(outputPath, content, 'utf-8');
}

export function generateShortDiffSummary(diffResult: DiffResult): string {
  const parts: string[] = [];

  if (diffResult.summary.filesChanged > 0) {
    parts.push(`${diffResult.summary.filesChanged} file(s)`);
  }
  if (diffResult.summary.additions > 0) {
    parts.push(`+${diffResult.summary.additions}`);
  }
  if (diffResult.summary.deletions > 0) {
    parts.push(`-${diffResult.summary.deletions}`);
  }

  return parts.length > 0 ? parts.join(' ') : 'No changes';
}

export function highlightDiffLine(line: string): string {
  if (line.startsWith('+')) {
    return `\x1b[32m${line}\x1b[0m`;
  }
  if (line.startsWith('-')) {
    return `\x1b[31m${line}\x1b[0m`;
  }
  if (line.startsWith('@@')) {
    return `\x1b[36m${line}\x1b[0m`;
  }
  return line;
}

export function countDiffStats(diffContent: string): { additions: number; deletions: number; files: number } {
  let additions = 0;
  let deletions = 0;
  let files = 0;

  const lines = diffContent.split('\n');
  for (const line of lines) {
    if (line.startsWith('+') && !line.startsWith('+++')) {
      additions++;
    } else if (line.startsWith('-') && !line.startsWith('---')) {
      deletions++;
    } else if (line.startsWith('diff --git')) {
      files++;
    }
  }

  return { additions, deletions, files: files || 1 };
}

export function parseFileDiff(
  filePath: string,
  oldContent: string,
  newContent: string
): DiffFile {
  const changes: DiffLine[] = [];
  const oldLines = oldContent.split('\n');
  const newLines = newContent.split('\n');

  const lcs = computeLCS(oldLines, newLines);

  let oldIdx = 0;
  let newIdx = 0;

  for (const [oldI, newI] of lcs) {
    while (oldIdx < oldI) {
      changes.push({
        type: 'deleted',
        lineNumber: { old: oldIdx + 1, new: null },
        content: `-${oldLines[oldIdx]}`
      });
      oldIdx++;
    }

    while (newIdx < newI) {
      changes.push({
        type: 'added',
        lineNumber: { old: null, new: newIdx + 1 },
        content: `+${newLines[newIdx]}`
      });
      newIdx++;
    }

    changes.push({
      type: 'context',
      lineNumber: { old: oldIdx + 1, new: newIdx + 1 },
      content: ` ${oldLines[oldIdx]}`
    });
    oldIdx++;
    newIdx++;
  }

  while (oldIdx < oldLines.length) {
    changes.push({
      type: 'deleted',
      lineNumber: { old: oldIdx + 1, new: null },
      content: `-${oldLines[oldIdx]}`
    });
    oldIdx++;
  }

  while (newIdx < newLines.length) {
    changes.push({
      type: 'added',
      lineNumber: { old: null, new: newIdx + 1 },
      content: `+${newLines[newIdx]}`
    });
    newIdx++;
  }

  return {
    file: filePath,
    changes,
    additions: changes.filter(c => c.type === 'added').length,
    deletions: changes.filter(c => c.type === 'deleted').length
  };
}

function computeLCS(
  a: string[],
  b: string[]
): [number, number][] {
  const m = a.length;
  const n = b.length;
  const dp: number[][] = Array(m + 1).fill(null).map(() => Array(n + 1).fill(0));

  for (let i = 1; i <= m; i++) {
    for (let j = 1; j <= n; j++) {
      if (a[i - 1] === b[j - 1]) {
        dp[i][j] = dp[i - 1][j - 1] + 1;
      } else {
        dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
      }
    }
  }

  const lcs: [number, number][] = [];
  let i = m;
  let j = n;

  while (i > 0 && j > 0) {
    if (a[i - 1] === b[j - 1]) {
      lcs.unshift([i - 1, j - 1]);
      i--;
      j--;
    } else if (dp[i - 1][j] > dp[i][j - 1]) {
      i--;
    } else {
      j--;
    }
  }

  return lcs;
}