"""
GitHub Repository Crawler for Legal Templates.

Crawls GitHub and GitLab repositories to extract legal template documents
(Markdown, HTML, JSON, etc.) for ingestion into the RAG system.

Features:
- Clone repositories via Git or download as ZIP
- Parse Markdown, HTML, JSON, and plain text files
- Extract structured content with metadata
- Track git commit hashes for reproducibility
- Handle rate limiting and errors gracefully
"""

import asyncio
import hashlib
import json
import logging
import os
import re
import shutil
import tempfile
import zipfile
from dataclasses import dataclass, field
from datetime import datetime
from fnmatch import fnmatch
from pathlib import Path
from typing import Any, AsyncGenerator, Dict, List, Optional, Tuple
from urllib.parse import urlparse

import httpx

from template_sources import LicenseType, SourceConfig, LICENSES

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Configuration
GITHUB_API_URL = "https://api.github.com"
GITLAB_API_URL = "https://gitlab.com/api/v4"
GITHUB_TOKEN = os.getenv("GITHUB_TOKEN", "")  # Optional for higher rate limits
MAX_FILE_SIZE = 1024 * 1024  # 1 MB max file size
REQUEST_TIMEOUT = 60.0
RATE_LIMIT_DELAY = 1.0  # Delay between requests to avoid rate limiting


@dataclass
class ExtractedDocument:
    """A document extracted from a repository."""
    text: str
    title: str
    file_path: str
    file_type: str  # "markdown", "html", "json", "text"
    source_url: str
    source_commit: Optional[str] = None
    source_hash: str = ""  # SHA256 of original content
    sections: List[Dict[str, Any]] = field(default_factory=list)
    placeholders: List[str] = field(default_factory=list)
    language: str = "en"
    metadata: Dict[str, Any] = field(default_factory=dict)

    def __post_init__(self):
        if not self.source_hash and self.text:
            self.source_hash = hashlib.sha256(self.text.encode()).hexdigest()


class MarkdownParser:
    """Parse Markdown files into structured content."""

    # Common placeholder patterns
    PLACEHOLDER_PATTERNS = [
        r'\[([A-Z_]+)\]',  # [COMPANY_NAME]
        r'\{([a-z_]+)\}',  # {company_name}
        r'\{\{([a-z_]+)\}\}',  # {{company_name}}
        r'__([A-Z_]+)__',  # __COMPANY_NAME__
        r'<([A-Z_]+)>',  # <COMPANY_NAME>
    ]

    @classmethod
    def parse(cls, content: str, filename: str = "") -> ExtractedDocument:
        """Parse markdown content into an ExtractedDocument."""
        # Extract title from first heading or filename
        title = cls._extract_title(content, filename)

        # Extract sections
        sections = cls._extract_sections(content)

        # Find placeholders
        placeholders = cls._find_placeholders(content)

        # Detect language
        language = cls._detect_language(content)

        # Clean content for indexing
        clean_text = cls._clean_for_indexing(content)

        return ExtractedDocument(
            text=clean_text,
            title=title,
            file_path=filename,
            file_type="markdown",
            source_url="",  # Will be set by caller
            sections=sections,
            placeholders=placeholders,
            language=language,
        )

    @classmethod
    def _extract_title(cls, content: str, filename: str) -> str:
        """Extract title from markdown heading or filename."""
        # Look for first h1 heading
        h1_match = re.search(r'^#\s+(.+)$', content, re.MULTILINE)
        if h1_match:
            return h1_match.group(1).strip()

        # Look for YAML frontmatter title
        frontmatter_match = re.search(
            r'^---\s*\n.*?title:\s*["\']?(.+?)["\']?\s*\n.*?---',
            content, re.DOTALL
        )
        if frontmatter_match:
            return frontmatter_match.group(1).strip()

        # Fall back to filename
        if filename:
            name = Path(filename).stem
            # Convert kebab-case or snake_case to title case
            return name.replace('-', ' ').replace('_', ' ').title()

        return "Untitled"

    @classmethod
    def _extract_sections(cls, content: str) -> List[Dict[str, Any]]:
        """Extract sections from markdown content."""
        sections = []
        current_section = {"heading": "", "level": 0, "content": "", "start": 0}

        for match in re.finditer(r'^(#{1,6})\s+(.+)$', content, re.MULTILINE):
            # Save previous section if it has content
            if current_section["heading"] or current_section["content"].strip():
                current_section["content"] = current_section["content"].strip()
                sections.append(current_section.copy())

            # Start new section
            level = len(match.group(1))
            heading = match.group(2).strip()
            current_section = {
                "heading": heading,
                "level": level,
                "content": "",
                "start": match.end(),
            }

        # Add final section
        if current_section["heading"] or current_section["content"].strip():
            current_section["content"] = content[current_section["start"]:].strip()
            sections.append(current_section)

        return sections

    @classmethod
    def _find_placeholders(cls, content: str) -> List[str]:
        """Find placeholder patterns in content."""
        placeholders = set()
        for pattern in cls.PLACEHOLDER_PATTERNS:
            for match in re.finditer(pattern, content):
                placeholder = match.group(0)
                placeholders.add(placeholder)
        return sorted(list(placeholders))

    @classmethod
    def _detect_language(cls, content: str) -> str:
        """Detect language from content."""
        # Look for German-specific words
        german_indicators = [
            'Datenschutz', 'Impressum', 'Nutzungsbedingungen', 'Haftung',
            'Widerruf', 'Verantwortlicher', 'personenbezogene', 'Verarbeitung',
            'und', 'der', 'die', 'das', 'ist', 'wird', 'werden', 'sind',
        ]

        lower_content = content.lower()
        german_count = sum(1 for word in german_indicators if word.lower() in lower_content)

        if german_count >= 3:
            return "de"
        return "en"

    @classmethod
    def _clean_for_indexing(cls, content: str) -> str:
        """Clean markdown content for text indexing."""
        # Remove YAML frontmatter
        content = re.sub(r'^---\s*\n.*?---\s*\n', '', content, flags=re.DOTALL)

        # Remove HTML comments
        content = re.sub(r'<!--.*?-->', '', content, flags=re.DOTALL)

        # Remove inline HTML tags but keep content
        content = re.sub(r'<[^>]+>', '', content)

        # Convert markdown formatting
        content = re.sub(r'\*\*(.+?)\*\*', r'\1', content)  # Bold
        content = re.sub(r'\*(.+?)\*', r'\1', content)  # Italic
        content = re.sub(r'`(.+?)`', r'\1', content)  # Inline code
        content = re.sub(r'~~(.+?)~~', r'\1', content)  # Strikethrough

        # Remove link syntax but keep text
        content = re.sub(r'\[([^\]]+)\]\([^)]+\)', r'\1', content)

        # Remove image syntax
        content = re.sub(r'!\[([^\]]*)\]\([^)]+\)', r'\1', content)

        # Clean up whitespace
        content = re.sub(r'\n{3,}', '\n\n', content)
        content = re.sub(r' +', ' ', content)

        return content.strip()


class HTMLParser:
    """Parse HTML files into structured content."""

    @classmethod
    def parse(cls, content: str, filename: str = "") -> ExtractedDocument:
        """Parse HTML content into an ExtractedDocument."""
        # Extract title
        title_match = re.search(r'<title>(.+?)</title>', content, re.IGNORECASE)
        title = title_match.group(1) if title_match else Path(filename).stem

        # Convert to text
        text = cls._html_to_text(content)

        # Find placeholders
        placeholders = MarkdownParser._find_placeholders(text)

        # Detect language
        lang_match = re.search(r'<html[^>]*lang=["\']([a-z]{2})["\']', content, re.IGNORECASE)
        language = lang_match.group(1) if lang_match else MarkdownParser._detect_language(text)

        return ExtractedDocument(
            text=text,
            title=title,
            file_path=filename,
            file_type="html",
            source_url="",
            placeholders=placeholders,
            language=language,
        )

    @classmethod
    def _html_to_text(cls, html: str) -> str:
        """Convert HTML to clean text."""
        # Remove script and style tags
        html = re.sub(r'<script[^>]*>.*?</script>', '', html, flags=re.DOTALL | re.IGNORECASE)
        html = re.sub(r'<style[^>]*>.*?</style>', '', html, flags=re.DOTALL | re.IGNORECASE)

        # Remove comments
        html = re.sub(r'<!--.*?-->', '', html, flags=re.DOTALL)

        # Replace common entities
        html = html.replace('&nbsp;', ' ')
        html = html.replace('&amp;', '&')
        html = html.replace('&lt;', '<')
        html = html.replace('&gt;', '>')
        html = html.replace('&quot;', '"')
        html = html.replace('&apos;', "'")

        # Add line breaks for block elements
        html = re.sub(r'<br\s*/?>', '\n', html, flags=re.IGNORECASE)
        html = re.sub(r'</p>', '\n\n', html, flags=re.IGNORECASE)
        html = re.sub(r'</div>', '\n', html, flags=re.IGNORECASE)
        html = re.sub(r'</h[1-6]>', '\n\n', html, flags=re.IGNORECASE)
        html = re.sub(r'</li>', '\n', html, flags=re.IGNORECASE)

        # Remove remaining tags
        html = re.sub(r'<[^>]+>', '', html)

        # Clean whitespace
        html = re.sub(r'[ \t]+', ' ', html)
        html = re.sub(r'\n[ \t]+', '\n', html)
        html = re.sub(r'[ \t]+\n', '\n', html)
        html = re.sub(r'\n{3,}', '\n\n', html)

        return html.strip()


class JSONParser:
    """Parse JSON files containing legal template data."""

    @classmethod
    def parse(cls, content: str, filename: str = "") -> List[ExtractedDocument]:
        """Parse JSON content into ExtractedDocuments."""
        try:
            data = json.loads(content)
        except json.JSONDecodeError as e:
            logger.warning(f"Failed to parse JSON from {filename}: {e}")
            return []

        documents = []

        if isinstance(data, dict):
            # Handle different JSON structures
            documents.extend(cls._parse_dict(data, filename))
        elif isinstance(data, list):
            for i, item in enumerate(data):
                if isinstance(item, dict):
                    docs = cls._parse_dict(item, f"{filename}[{i}]")
                    documents.extend(docs)

        return documents

    @classmethod
    def _parse_dict(cls, data: dict, filename: str) -> List[ExtractedDocument]:
        """Parse a dictionary into documents."""
        documents = []

        # Look for text content in common keys
        text_keys = ['text', 'content', 'body', 'description', 'value']
        title_keys = ['title', 'name', 'heading', 'label', 'key']

        # Try to find main text content
        text = ""
        for key in text_keys:
            if key in data and isinstance(data[key], str):
                text = data[key]
                break

        if not text:
            # Check for nested structures (like webflorist format)
            for key, value in data.items():
                if isinstance(value, dict):
                    nested_docs = cls._parse_dict(value, f"{filename}.{key}")
                    documents.extend(nested_docs)
                elif isinstance(value, list):
                    for i, item in enumerate(value):
                        if isinstance(item, dict):
                            nested_docs = cls._parse_dict(item, f"{filename}.{key}[{i}]")
                            documents.extend(nested_docs)
                        elif isinstance(item, str) and len(item) > 50:
                            # Treat long strings as content
                            documents.append(ExtractedDocument(
                                text=item,
                                title=f"{key} {i+1}",
                                file_path=filename,
                                file_type="json",
                                source_url="",
                                language=MarkdownParser._detect_language(item),
                            ))
            return documents

        # Found text content
        title = ""
        for key in title_keys:
            if key in data and isinstance(data[key], str):
                title = data[key]
                break

        if not title:
            title = Path(filename).stem

        # Extract metadata
        metadata = {}
        for key, value in data.items():
            if key not in text_keys + title_keys and not isinstance(value, (dict, list)):
                metadata[key] = value

        placeholders = MarkdownParser._find_placeholders(text)
        language = data.get('lang', data.get('language', MarkdownParser._detect_language(text)))

        documents.append(ExtractedDocument(
            text=text,
            title=title,
            file_path=filename,
            file_type="json",
            source_url="",
            placeholders=placeholders,
            language=language,
            metadata=metadata,
        ))

        return documents


class GitHubCrawler:
    """Crawl GitHub repositories for legal templates."""

    def __init__(self, token: Optional[str] = None):
        self.token = token or GITHUB_TOKEN
        self.headers = {
            "Accept": "application/vnd.github.v3+json",
            "User-Agent": "LegalTemplatesCrawler/1.0",
        }
        if self.token:
            self.headers["Authorization"] = f"token {self.token}"

        self.http_client: Optional[httpx.AsyncClient] = None

    async def __aenter__(self):
        self.http_client = httpx.AsyncClient(
            timeout=REQUEST_TIMEOUT,
            headers=self.headers,
            follow_redirects=True,
        )
        return self

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        if self.http_client:
            await self.http_client.aclose()

    def _parse_repo_url(self, url: str) -> Tuple[str, str, str]:
        """Parse repository URL into owner, repo, and host."""
        parsed = urlparse(url)
        path_parts = parsed.path.strip('/').split('/')

        if len(path_parts) < 2:
            raise ValueError(f"Invalid repository URL: {url}")

        owner = path_parts[0]
        repo = path_parts[1].replace('.git', '')

        if 'gitlab' in parsed.netloc:
            host = 'gitlab'
        else:
            host = 'github'

        return owner, repo, host

    async def get_default_branch(self, owner: str, repo: str) -> str:
        """Get the default branch of a repository."""
        if not self.http_client:
            raise RuntimeError("Crawler not initialized. Use 'async with' context.")

        url = f"{GITHUB_API_URL}/repos/{owner}/{repo}"
        response = await self.http_client.get(url)
        response.raise_for_status()
        data = response.json()
        return data.get("default_branch", "main")

    async def get_latest_commit(self, owner: str, repo: str, branch: str = "main") -> str:
        """Get the latest commit SHA for a branch."""
        if not self.http_client:
            raise RuntimeError("Crawler not initialized. Use 'async with' context.")

        url = f"{GITHUB_API_URL}/repos/{owner}/{repo}/commits/{branch}"
        response = await self.http_client.get(url)
        response.raise_for_status()
        data = response.json()
        return data.get("sha", "")

    async def list_files(
        self,
        owner: str,
        repo: str,
        path: str = "",
        branch: str = "main",
        patterns: List[str] = None,
        exclude_patterns: List[str] = None,
    ) -> List[Dict[str, Any]]:
        """List files in a repository matching the given patterns."""
        if not self.http_client:
            raise RuntimeError("Crawler not initialized. Use 'async with' context.")

        patterns = patterns or ["*.md", "*.txt", "*.html"]
        exclude_patterns = exclude_patterns or []

        url = f"{GITHUB_API_URL}/repos/{owner}/{repo}/git/trees/{branch}?recursive=1"
        response = await self.http_client.get(url)
        response.raise_for_status()
        data = response.json()

        files = []
        for item in data.get("tree", []):
            if item["type"] != "blob":
                continue

            file_path = item["path"]

            # Check exclude patterns
            excluded = any(fnmatch(file_path, pattern) for pattern in exclude_patterns)
            if excluded:
                continue

            # Check include patterns
            matched = any(fnmatch(file_path, pattern) for pattern in patterns)
            if not matched:
                continue

            # Skip large files
            if item.get("size", 0) > MAX_FILE_SIZE:
                logger.warning(f"Skipping large file: {file_path} ({item['size']} bytes)")
                continue

            files.append({
                "path": file_path,
                "sha": item["sha"],
                "size": item.get("size", 0),
                "url": item.get("url", ""),
            })

        return files

    async def get_file_content(self, owner: str, repo: str, path: str, branch: str = "main") -> str:
        """Get the content of a file from a repository."""
        if not self.http_client:
            raise RuntimeError("Crawler not initialized. Use 'async with' context.")

        # Use raw content URL for simplicity
        url = f"https://raw.githubusercontent.com/{owner}/{repo}/{branch}/{path}"
        response = await self.http_client.get(url)
        response.raise_for_status()
        return response.text

    async def crawl_repository(
        self,
        source: SourceConfig,
    ) -> AsyncGenerator[ExtractedDocument, None]:
        """Crawl a repository and yield extracted documents."""
        if not source.repo_url:
            logger.warning(f"No repo URL for source: {source.name}")
            return

        try:
            owner, repo, host = self._parse_repo_url(source.repo_url)
        except ValueError as e:
            logger.error(f"Failed to parse repo URL for {source.name}: {e}")
            return

        if host == "gitlab":
            logger.info(f"GitLab repos not yet supported: {source.name}")
            return

        logger.info(f"Crawling repository: {owner}/{repo}")

        try:
            # Get default branch and latest commit
            branch = await self.get_default_branch(owner, repo)
            commit_sha = await self.get_latest_commit(owner, repo, branch)

            await asyncio.sleep(RATE_LIMIT_DELAY)

            # List files matching patterns
            files = await self.list_files(
                owner, repo,
                branch=branch,
                patterns=source.file_patterns,
                exclude_patterns=source.exclude_patterns,
            )

            logger.info(f"Found {len(files)} matching files in {source.name}")

            for file_info in files:
                await asyncio.sleep(RATE_LIMIT_DELAY)

                try:
                    content = await self.get_file_content(
                        owner, repo, file_info["path"], branch
                    )

                    # Parse based on file type
                    file_path = file_info["path"]
                    source_url = f"https://github.com/{owner}/{repo}/blob/{branch}/{file_path}"

                    if file_path.endswith('.md'):
                        doc = MarkdownParser.parse(content, file_path)
                        doc.source_url = source_url
                        doc.source_commit = commit_sha
                        yield doc

                    elif file_path.endswith('.html') or file_path.endswith('.htm'):
                        doc = HTMLParser.parse(content, file_path)
                        doc.source_url = source_url
                        doc.source_commit = commit_sha
                        yield doc

                    elif file_path.endswith('.json'):
                        docs = JSONParser.parse(content, file_path)
                        for doc in docs:
                            doc.source_url = source_url
                            doc.source_commit = commit_sha
                            yield doc

                    elif file_path.endswith('.txt'):
                        # Plain text file
                        yield ExtractedDocument(
                            text=content,
                            title=Path(file_path).stem,
                            file_path=file_path,
                            file_type="text",
                            source_url=source_url,
                            source_commit=commit_sha,
                            language=MarkdownParser._detect_language(content),
                            placeholders=MarkdownParser._find_placeholders(content),
                        )

                except httpx.HTTPError as e:
                    logger.warning(f"Failed to fetch {file_path}: {e}")
                    continue
                except Exception as e:
                    logger.error(f"Error processing {file_path}: {e}")
                    continue

        except httpx.HTTPError as e:
            logger.error(f"HTTP error crawling {source.name}: {e}")
        except Exception as e:
            logger.error(f"Error crawling {source.name}: {e}")


class RepositoryDownloader:
    """Download and extract repository archives."""

    def __init__(self):
        self.http_client: Optional[httpx.AsyncClient] = None

    async def __aenter__(self):
        self.http_client = httpx.AsyncClient(
            timeout=120.0,
            follow_redirects=True,
        )
        return self

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        if self.http_client:
            await self.http_client.aclose()

    async def download_zip(self, repo_url: str, branch: str = "main") -> Path:
        """Download repository as ZIP and extract to temp directory."""
        if not self.http_client:
            raise RuntimeError("Downloader not initialized. Use 'async with' context.")

        parsed = urlparse(repo_url)
        path_parts = parsed.path.strip('/').split('/')
        owner = path_parts[0]
        repo = path_parts[1].replace('.git', '')

        zip_url = f"https://github.com/{owner}/{repo}/archive/refs/heads/{branch}.zip"

        logger.info(f"Downloading ZIP from {zip_url}")

        response = await self.http_client.get(zip_url)
        response.raise_for_status()

        # Save to temp file
        temp_dir = Path(tempfile.mkdtemp())
        zip_path = temp_dir / f"{repo}.zip"

        with open(zip_path, 'wb') as f:
            f.write(response.content)

        # Extract ZIP
        extract_dir = temp_dir / repo
        with zipfile.ZipFile(zip_path, 'r') as zip_ref:
            zip_ref.extractall(temp_dir)

        # The extracted directory is usually named repo-branch
        extracted_dirs = list(temp_dir.glob(f"{repo}-*"))
        if extracted_dirs:
            return extracted_dirs[0]

        return extract_dir

    async def crawl_local_directory(
        self,
        directory: Path,
        source: SourceConfig,
        base_url: str,
    ) -> AsyncGenerator[ExtractedDocument, None]:
        """Crawl a local directory for documents."""
        patterns = source.file_patterns or ["*.md", "*.txt", "*.html"]
        exclude_patterns = source.exclude_patterns or []

        for pattern in patterns:
            for file_path in directory.rglob(pattern.replace("**/", "")):
                if not file_path.is_file():
                    continue

                rel_path = str(file_path.relative_to(directory))

                # Check exclude patterns
                excluded = any(fnmatch(rel_path, ep) for ep in exclude_patterns)
                if excluded:
                    continue

                # Skip large files
                if file_path.stat().st_size > MAX_FILE_SIZE:
                    continue

                try:
                    content = file_path.read_text(encoding='utf-8')
                except UnicodeDecodeError:
                    try:
                        content = file_path.read_text(encoding='latin-1')
                    except Exception:
                        continue

                source_url = f"{base_url}/{rel_path}"

                if file_path.suffix == '.md':
                    doc = MarkdownParser.parse(content, rel_path)
                    doc.source_url = source_url
                    yield doc

                elif file_path.suffix in ['.html', '.htm']:
                    doc = HTMLParser.parse(content, rel_path)
                    doc.source_url = source_url
                    yield doc

                elif file_path.suffix == '.json':
                    docs = JSONParser.parse(content, rel_path)
                    for doc in docs:
                        doc.source_url = source_url
                        yield doc

                elif file_path.suffix == '.txt':
                    yield ExtractedDocument(
                        text=content,
                        title=file_path.stem,
                        file_path=rel_path,
                        file_type="text",
                        source_url=source_url,
                        language=MarkdownParser._detect_language(content),
                        placeholders=MarkdownParser._find_placeholders(content),
                    )

    def cleanup(self, directory: Path):
        """Clean up temporary directory."""
        if directory.exists():
            shutil.rmtree(directory, ignore_errors=True)


async def crawl_source(source: SourceConfig) -> List[ExtractedDocument]:
    """Crawl a source configuration and return all extracted documents."""
    documents = []

    if source.repo_url:
        async with GitHubCrawler() as crawler:
            async for doc in crawler.crawl_repository(source):
                documents.append(doc)

    return documents


# CLI for testing
async def main():
    """Test crawler with a sample source."""
    from template_sources import TEMPLATE_SOURCES

    # Test with github-site-policy
    source = next(s for s in TEMPLATE_SOURCES if s.name == "github-site-policy")

    async with GitHubCrawler() as crawler:
        count = 0
        async for doc in crawler.crawl_repository(source):
            count += 1
            print(f"\n{'='*60}")
            print(f"Title: {doc.title}")
            print(f"Path: {doc.file_path}")
            print(f"Type: {doc.file_type}")
            print(f"Language: {doc.language}")
            print(f"URL: {doc.source_url}")
            print(f"Placeholders: {doc.placeholders[:5] if doc.placeholders else 'None'}")
            print(f"Text preview: {doc.text[:200]}...")

        print(f"\n\nTotal documents: {count}")


if __name__ == "__main__":
    asyncio.run(main())