"""Codebase analyzer - gathers structure and context for task decomposition."""

import os
import subprocess
from dataclasses import dataclass, field
from pathlib import Path


@dataclass
class CodebaseInfo:
    """Summary of a codebase's structure and key files."""
    root: Path
    languages: dict[str, int] = field(default_factory=dict)  # extension -> file count
    total_files: int = 0
    total_lines: int = 0
    tree: list[str] = field(default_factory=list)  # directory tree (paths)
    key_files: list[str] = field(default_factory=list)  # config, entry points, etc.
    git_branch: str = ""
    recent_commits: list[str] = field(default_factory=list)

    def summary(self) -> str:
        lines = [f"Codebase: {self.root.name}"]
        if self.git_branch:
            lines.append(f"Branch: {self.git_branch}")
        lines.append(f"Files: {self.total_files} | Lines: ~{self.total_lines}")
        if self.languages:
            top = sorted(self.languages.items(), key=lambda x: -x[1])[:5]
            lines.append("Languages: " + ", ".join(f"{ext} ({n})" for ext, n in top))
        if self.key_files:
            lines.append("Key files: " + ", ".join(self.key_files[:10]))
        return "\n".join(lines)


IGNORE_DIRS = {
    ".git", "node_modules", "__pycache__", ".venv", "venv", "dist", "build",
    ".next", ".nuxt", "target", "vendor", ".tox", ".mypy_cache", ".pytest_cache",
    "coverage", ".cache", "env", ".env", ".eggs", "*.egg-info",
}

KEY_FILE_NAMES = {
    "package.json", "pyproject.toml", "setup.py", "setup.cfg", "Cargo.toml",
    "go.mod", "Makefile", "CMakeLists.txt", "Dockerfile", "docker-compose.yml",
    "docker-compose.yaml", ".env.example", "requirements.txt", "tsconfig.json",
    "webpack.config.js", "vite.config.ts", "vite.config.js", "next.config.js",
    "tailwind.config.js", "CLAUDE.md",
}


def analyze_codebase(root: Path) -> CodebaseInfo:
    """Walk the codebase and gather structural info."""
    info = CodebaseInfo(root=root.resolve())

    # Git info
    try:
        info.git_branch = subprocess.check_output(
            ["git", "rev-parse", "--abbrev-ref", "HEAD"],
            cwd=root, stderr=subprocess.DEVNULL, text=True,
        ).strip()
    except (subprocess.CalledProcessError, FileNotFoundError):
        pass

    try:
        log = subprocess.check_output(
            ["git", "log", "--oneline", "-10"],
            cwd=root, stderr=subprocess.DEVNULL, text=True,
        ).strip()
        if log:
            info.recent_commits = log.splitlines()
    except (subprocess.CalledProcessError, FileNotFoundError):
        pass

    # Walk files
    languages: dict[str, int] = {}
    total_lines = 0

    for dirpath, dirnames, filenames in os.walk(root):
        # Prune ignored directories
        dirnames[:] = [d for d in dirnames if d not in IGNORE_DIRS]

        rel_dir = os.path.relpath(dirpath, root)

        for fname in filenames:
            full = os.path.join(dirpath, fname)
            rel = os.path.join(rel_dir, fname) if rel_dir != "." else fname
            info.tree.append(rel)
            info.total_files += 1

            # Check key files
            if fname in KEY_FILE_NAMES:
                info.key_files.append(rel)

            # Language stats
            ext = Path(fname).suffix.lower()
            if ext:
                languages[ext] = languages.get(ext, 0) + 1

            # Line count (skip binary)
            try:
                with open(full, "r", errors="ignore") as f:
                    total_lines += sum(1 for _ in f)
            except (OSError, UnicodeDecodeError):
                pass

    info.languages = languages
    info.total_lines = total_lines
    return info