"""Generator for combining gitignore patterns."""

from pathlib import Path
from typing import Optional

from .api import get_patterns_batch
from .cache import CacheManager


class GitignoreGenerator:
    """Generates combined .gitignore files from multiple tech stacks."""

    def __init__(self, custom_patterns_file: Optional[str] = None):
        """Initialize generator.

        Args:
            custom_patterns_file: Path to custom patterns file
        """
        self.cache = CacheManager()
        self.custom_patterns_file = custom_patterns_file

    def load_custom_patterns(self) -> list[str]:
        """Load custom patterns from file.

        Returns:
            List of custom patterns
        """
        if self.custom_patterns_file:
            path = Path(self.custom_patterns_file)
            if path.exists():
                return path.read_text().splitlines()
        return []

    def combine_patterns(
        self,
        techs: list[str],
        add_patterns: Optional[list[str]] = None,
        force_refresh: bool = False
    ) -> str:
        """Combine gitignore patterns from multiple technologies.

        Args:
            techs: List of technology names
            add_patterns: Additional patterns to add
            force_refresh: Force refresh from API

        Returns:
            Combined gitignore content
        """
        patterns = get_patterns_batch(techs, force_refresh)

        output_lines = []
        seen_patterns = set()

        for tech in techs:
            pattern_content = patterns.get(tech, '').strip()
            if pattern_content:
                output_lines.append(f"# --- {tech.upper()} ---")
                for line in pattern_content.splitlines():
                    line = line.strip()
                    if line and not line.startswith('#'):
                        if line not in seen_patterns:
                            seen_patterns.add(line)
                            output_lines.append(line)
                output_lines.append("")

        custom_patterns = self.load_custom_patterns()
        if add_patterns:
            custom_patterns.extend(add_patterns)

        if custom_patterns:
            output_lines.append("# --- CUSTOM ---")
            for pattern in custom_patterns:
                pattern = pattern.strip()
                if pattern and not pattern.startswith('#'):
                    if pattern not in seen_patterns:
                        seen_patterns.add(pattern)
                        output_lines.append(pattern)
            output_lines.append("")

        return '\n'.join(output_lines).strip()

    def generate_file(
        self,
        techs: list[str],
        output_path: Optional[str] = None,
        preview: bool = False,
        add_patterns: Optional[list[str]] = None,
        force_refresh: bool = False
    ) -> str:
        """Generate gitignore file.

        Args:
            techs: List of technology names
            output_path: Path to write file (None for stdout)
            preview: If True, return content without writing
            add_patterns: Additional patterns to add
            force_refresh: Force refresh from API

        Returns:
            Generated gitignore content
        """
        content = self.combine_patterns(techs, add_patterns, force_refresh)

        if preview or output_path is None:
            return content

        output_file = Path(output_path)
        output_file.parent.mkdir(parents=True, exist_ok=True)
        output_file.write_text(content + '\n')

        return content

    def merge_with_existing(
        self,
        existing_path: str,
        techs: list[str],
        add_patterns: Optional[list[str]] = None,
        force_refresh: bool = False
    ) -> str:
        """Merge generated patterns with existing .gitignore.

        Args:
            existing_path: Path to existing .gitignore
            techs: List of technology names
            add_patterns: Additional patterns to add
            force_refresh: Force refresh from API

        Returns:
            Merged gitignore content
        """
        existing_content = ""
        existing_file = Path(existing_path)
        if existing_file.exists():
            existing_content = existing_file.read_text()

        existing_lines = set()
        for line in existing_content.splitlines():
            line = line.strip()
            if line and not line.startswith('#'):
                existing_lines.add(line)

        new_content = self.combine_patterns(techs, add_patterns, force_refresh)

        output_lines = []
        if existing_content.strip():
            output_lines.append("# --- EXISTING ---")
            output_lines.append(existing_content.strip())
            output_lines.append("")

        output_lines.append("# --- GENERATED ---")
        output_lines.append(new_content)

        return '\n'.join(output_lines).strip()


def generate_gitignore(
    techs: list[str],
    output_path: Optional[str] = None,
    preview: bool = False,
    add_patterns: Optional[list[str]] = None,
    force_refresh: bool = False
) -> str:
    """Convenience function to generate gitignore.

    Args:
        techs: List of technology names
        output_path: Path to write file (None for stdout)
        preview: If True, return content without writing
        add_patterns: Additional patterns to add
        force_refresh: Force refresh from API

    Returns:
        Generated gitignore content
    """
    generator = GitignoreGenerator()
    return generator.generate_file(
        techs, output_path, preview, add_patterns, force_refresh
    )