#!/usr/bin/env python3
"""
Common path utilities for Trellis workflow.

Provides:
    get_repo_root          - Get repository root directory
    get_developer          - Get developer name
    get_workspace_dir      - Get developer workspace directory
    get_tasks_dir          - Get tasks directory
    get_active_journal_file - Get current journal file
"""

from __future__ import annotations

import re
from datetime import datetime
from pathlib import Path


# =============================================================================
# Path Constants (change here to rename directories)
# =============================================================================

# Directory names
DIR_WORKFLOW = ".trellis"
DIR_WORKSPACE = "workspace"
DIR_TASKS = "tasks"
DIR_ARCHIVE = "archive"
DIR_SPEC = "spec"
DIR_SCRIPTS = "scripts"

# File names
FILE_DEVELOPER = ".developer"
FILE_CURRENT_TASK = ".current-task"
FILE_TASK_JSON = "task.json"
FILE_JOURNAL_PREFIX = "journal-"


# =============================================================================
# Repository Root
# =============================================================================

def get_repo_root(start_path: Path | None = None) -> Path:
    """Find the nearest directory containing .trellis/ folder.

    This handles nested git repos correctly (e.g., test project inside another repo).

    Args:
        start_path: Starting directory to search from. Defaults to current directory.

    Returns:
        Path to repository root, or current directory if no .trellis/ found.
    """
    current = (start_path or Path.cwd()).resolve()

    while current != current.parent:
        if (current / DIR_WORKFLOW).is_dir():
            return current
        current = current.parent

    # Fallback to current directory if no .trellis/ found
    return Path.cwd().resolve()


# =============================================================================
# Developer
# =============================================================================

def get_developer(repo_root: Path | None = None) -> str | None:
    """Get developer name from .developer file.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Developer name or None if not initialized.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    dev_file = repo_root / DIR_WORKFLOW / FILE_DEVELOPER

    if not dev_file.is_file():
        return None

    try:
        content = dev_file.read_text(encoding="utf-8")
        for line in content.splitlines():
            if line.startswith("name="):
                return line.split("=", 1)[1].strip()
    except (OSError, IOError):
        pass

    return None


def check_developer(repo_root: Path | None = None) -> bool:
    """Check if developer is initialized.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        True if developer is initialized.
    """
    return get_developer(repo_root) is not None


# =============================================================================
# Tasks Directory
# =============================================================================

def get_tasks_dir(repo_root: Path | None = None) -> Path:
    """Get tasks directory path.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Path to tasks directory.
    """
    if repo_root is None:
        repo_root = get_repo_root()
    return repo_root / DIR_WORKFLOW / DIR_TASKS


# =============================================================================
# Workspace Directory
# =============================================================================

def get_workspace_dir(repo_root: Path | None = None) -> Path | None:
    """Get developer workspace directory.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Path to workspace directory or None if developer not set.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    developer = get_developer(repo_root)
    if developer:
        return repo_root / DIR_WORKFLOW / DIR_WORKSPACE / developer
    return None


# =============================================================================
# Journal File
# =============================================================================

def get_active_journal_file(repo_root: Path | None = None) -> Path | None:
    """Get the current active journal file.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Path to active journal file or None if not found.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    workspace_dir = get_workspace_dir(repo_root)
    if workspace_dir is None or not workspace_dir.is_dir():
        return None

    latest: Path | None = None
    highest = 0

    for f in workspace_dir.glob(f"{FILE_JOURNAL_PREFIX}*.md"):
        if not f.is_file():
            continue

        # Extract number from filename
        name = f.stem  # e.g., "journal-1"
        match = re.search(r"(\d+)$", name)
        if match:
            num = int(match.group(1))
            if num > highest:
                highest = num
                latest = f

    return latest


def count_lines(file_path: Path) -> int:
    """Count lines in a file.

    Args:
        file_path: Path to file.

    Returns:
        Number of lines, or 0 if file doesn't exist.
    """
    if not file_path.is_file():
        return 0

    try:
        return len(file_path.read_text(encoding="utf-8").splitlines())
    except (OSError, IOError):
        return 0


# =============================================================================
# Current Task Management
# =============================================================================

def _get_current_task_file(repo_root: Path | None = None) -> Path:
    """Get .current-task file path.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Path to .current-task file.
    """
    if repo_root is None:
        repo_root = get_repo_root()
    return repo_root / DIR_WORKFLOW / FILE_CURRENT_TASK


def normalize_task_ref(task_ref: str) -> str:
    """Normalize a task ref for stable storage in .current-task.

    Stored refs should prefer repo-relative POSIX paths like
    `.trellis/tasks/03-27-my-task`, even on Windows. Absolute paths are preserved
    unless they can later be converted back to repo-relative form by callers.
    """
    normalized = task_ref.strip()
    if not normalized:
        return ""

    path_obj = Path(normalized)
    if path_obj.is_absolute():
        return str(path_obj)

    normalized = normalized.replace("\\", "/")
    while normalized.startswith("./"):
        normalized = normalized[2:]

    if normalized.startswith(f"{DIR_TASKS}/"):
        return f"{DIR_WORKFLOW}/{normalized}"

    return normalized


def resolve_task_ref(task_ref: str, repo_root: Path | None = None) -> Path | None:
    """Resolve a task ref from .current-task to an absolute task directory path."""
    if repo_root is None:
        repo_root = get_repo_root()

    normalized = normalize_task_ref(task_ref)
    if not normalized:
        return None

    path_obj = Path(normalized)
    if path_obj.is_absolute():
        return path_obj

    if normalized.startswith(f"{DIR_WORKFLOW}/"):
        return repo_root / path_obj

    return repo_root / DIR_WORKFLOW / DIR_TASKS / path_obj


def get_current_task(repo_root: Path | None = None) -> str | None:
    """Get current task directory path (relative to repo_root).

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Relative path to current task directory or None.
    """
    current_file = _get_current_task_file(repo_root)

    if not current_file.is_file():
        return None

    try:
        content = current_file.read_text(encoding="utf-8").strip()
        return normalize_task_ref(content) if content else None
    except (OSError, IOError):
        return None


def get_current_task_abs(repo_root: Path | None = None) -> Path | None:
    """Get current task directory absolute path.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        Absolute path to current task directory or None.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    relative = get_current_task(repo_root)
    if relative:
        return resolve_task_ref(relative, repo_root)
    return None


def set_current_task(task_path: str, repo_root: Path | None = None) -> bool:
    """Set current task.

    Args:
        task_path: Task directory path (relative to repo_root).
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        True on success, False on error.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    normalized = normalize_task_ref(task_path)
    if not normalized:
        return False

    # Verify task directory exists
    full_path = resolve_task_ref(normalized, repo_root)
    if full_path is None or not full_path.is_dir():
        return False

    try:
        normalized = full_path.relative_to(repo_root).as_posix()
    except ValueError:
        normalized = str(full_path)

    current_file = _get_current_task_file(repo_root)

    try:
        current_file.write_text(normalized, encoding="utf-8")
        return True
    except (OSError, IOError):
        return False


def clear_current_task(repo_root: Path | None = None) -> bool:
    """Clear current task.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        True on success.
    """
    current_file = _get_current_task_file(repo_root)

    try:
        if current_file.is_file():
            current_file.unlink()
        return True
    except (OSError, IOError):
        return False


def has_current_task(repo_root: Path | None = None) -> bool:
    """Check if has current task.

    Args:
        repo_root: Repository root path. Defaults to auto-detected.

    Returns:
        True if current task is set.
    """
    return get_current_task(repo_root) is not None


# =============================================================================
# Task ID Generation
# =============================================================================

def generate_task_date_prefix() -> str:
    """Generate task ID based on date (MM-DD format).

    Returns:
        Date prefix string (e.g., "01-21").
    """
    return datetime.now().strftime("%m-%d")


# =============================================================================
# Monorepo / Package Paths
# =============================================================================


def get_spec_dir(package: str | None = None, repo_root: Path | None = None) -> Path:
    """Get the spec directory path.

    Single-repo: .trellis/spec
    Monorepo with package: .trellis/spec/<package>

    Uses lazy import to avoid circular dependency with config.py.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    from .config import get_spec_base

    base = get_spec_base(package, repo_root)
    return repo_root / DIR_WORKFLOW / base


def get_package_path(package: str, repo_root: Path | None = None) -> Path | None:
    """Get a package's source directory absolute path from config.

    Returns:
        Absolute path to the package directory, or None if not found.
    """
    if repo_root is None:
        repo_root = get_repo_root()

    from .config import get_packages

    packages = get_packages(repo_root)
    if not packages or package not in packages:
        return None

    info = packages[package]
    if isinstance(info, dict):
        rel_path = info.get("path", package)
    else:
        rel_path = str(info)

    return repo_root / rel_path


# =============================================================================
# Main Entry (for testing)
# =============================================================================

if __name__ == "__main__":
    repo = get_repo_root()
    print(f"Repository root: {repo}")
    print(f"Developer: {get_developer(repo)}")
    print(f"Tasks dir: {get_tasks_dir(repo)}")
    print(f"Workspace dir: {get_workspace_dir(repo)}")
    print(f"Journal file: {get_active_journal_file(repo)}")
    print(f"Current task: {get_current_task(repo)}")