"""System utilities: subprocess, tool detection, file operations."""
from __future__ import annotations

import json
import json5
import os
import shutil
import stat
import subprocess
import tempfile
import yaml
from pathlib import Path, PurePosixPath, PureWindowsPath
from typing import Any
from ._console import console

CLAUDE_LOCAL_PATH = Path.home() / ".claude" / "local" / "claude"
CLAUDE_NPM_LOCAL_PATH = Path.home() / ".claude" / "local" / "node_modules" / ".bin" / "claude"


def relative_extension_path_violation(value: Any) -> str | None:
    """Return why ``value`` is unsafe as an extension-relative ``file`` path.

    Single source of truth for the path-safety policy shared by
    ``ExtensionManifest._validate()`` (manifest-load validation) and
    ``CommandRegistrar.register_commands()`` (runtime guard), so the two cannot
    drift. Returns a human-readable reason string when ``value`` is unsafe, or
    ``None`` when it is an acceptable relative path within the extension
    directory.

    Policy: the value must be a non-empty string with no leading/trailing
    whitespace, no absolute/anchored form, and no ``..`` traversal. The value is
    evaluated under both POSIX and Windows path semantics because a native
    ``Path`` is OS-dependent (a ``PurePosixPath`` on POSIX does not interpret
    Windows drive/UNC forms, and ``C:foo`` is anchored but not ``is_absolute()``
    yet resolves against the CWD on its drive). Rejecting any non-empty anchor
    covers POSIX-absolute (``/abs``), Windows drive-relative (``C:foo``), Windows
    absolute (``C:\\foo``), and UNC/rooted forms.
    """
    if not isinstance(value, str) or not value:
        return "must be a non-empty string"
    if value.strip() != value:
        return "must not have leading or trailing whitespace"
    posix_path = PurePosixPath(value)
    win_path = PureWindowsPath(value)
    if (
        posix_path.anchor
        or win_path.anchor
        or ".." in posix_path.parts
        or ".." in win_path.parts
    ):
        return (
            "must be a relative path within the extension directory "
            "(no absolute paths, drive letters, or '..' segments)"
        )
    return None


def dump_frontmatter(data: dict[str, Any]) -> str:
    """Serialize skill/command frontmatter to a YAML string.

    Centralizes the dump options used for SKILL.md frontmatter: ``allow_unicode``
    preserves Unicode descriptions and ``sort_keys=False`` keeps key order, so no
    call site can silently drop either.
    """
    return yaml.safe_dump(data, sort_keys=False, allow_unicode=True).strip()


def run_command(
    cmd: list[str],
    check_return: bool = True,
    capture: bool = False,
    shell: bool = False,
) -> str | None:
    """Run a command without invoking a shell and optionally capture output.

    The ``shell`` parameter is kept in the signature so existing keyword
    callers (and the re-export from ``specify_cli``) don't raise ``TypeError``,
    but only the default ``shell=False`` is honoured. ``shell=True`` is
    rejected with ``ValueError`` rather than silently ignored, so the
    unsupported mode fails loudly instead of running with a different meaning.
    """
    if shell:
        raise ValueError(
            "run_command() does not support shell=True; pass argv as a list"
        )

    try:
        if capture:
            result = subprocess.run(cmd, check=check_return, capture_output=True, text=True)
            return result.stdout.strip()
        else:
            subprocess.run(cmd, check=check_return)
            return None
    except subprocess.CalledProcessError as e:
        if check_return:
            console.print(f"[red]Error running command:[/red] {' '.join(cmd)}")
            console.print(f"[red]Exit code:[/red] {e.returncode}")
            if hasattr(e, 'stderr') and e.stderr:
                console.print(f"[red]Error output:[/red] {e.stderr}")
            raise
        return None


def check_tool(tool: str, tracker=None) -> bool:
    """Check if a tool is installed. Optionally update tracker.

    Args:
        tool: Name of the tool to check
        tracker: StepTracker | None to update with results

    Returns:
        True if tool is found, False otherwise
    """
    # Special handling for Claude CLI local installs
    # See: https://github.com/github/spec-kit/issues/123
    # See: https://github.com/github/spec-kit/issues/550
    # Claude Code can be installed in two local paths:
    #   1. ~/.claude/local/claude          (after `claude migrate-installer`)
    #   2. ~/.claude/local/node_modules/.bin/claude  (npm-local install, e.g. via nvm)
    # Neither path may be on the system PATH, so we check them explicitly.
    if tool == "claude":
        if CLAUDE_LOCAL_PATH.is_file() or CLAUDE_NPM_LOCAL_PATH.is_file():
            if tracker:
                tracker.complete(tool, "available")
            return True

    # Per-integration executable resolution.
    if tool == "kiro-cli":
        # Kiro currently supports both executable names. Prefer kiro-cli and
        # accept kiro as a compatibility fallback.
        found = shutil.which("kiro-cli") is not None or shutil.which("kiro") is not None
    elif tool == "rovodev":
        found = shutil.which("acli") is not None
    else:
        found = shutil.which(tool) is not None

    if tracker:
        if found:
            tracker.complete(tool, "available")
        else:
            tracker.error(tool, "not found")

    return found



def handle_vscode_settings(sub_item, dest_file, rel_path, verbose=False, tracker=None) -> None:
    """Handle merging or copying of .vscode/settings.json files.

    Note: when merge produces changes, rewritten output is normalized JSON and
    existing JSONC comments/trailing commas are not preserved.
    """
    def log(message, color="green"):
        if verbose and not tracker:
            console.print(f"[{color}]{message}[/] {rel_path}")

    def atomic_write_json(target_file: Path, payload: dict[str, Any]) -> None:
        """Atomically write JSON while preserving existing mode bits when possible."""
        temp_path: Path | None = None
        try:
            with tempfile.NamedTemporaryFile(
                mode='w',
                encoding='utf-8',
                dir=target_file.parent,
                prefix=f"{target_file.name}.",
                suffix=".tmp",
                delete=False,
            ) as f:
                temp_path = Path(f.name)
                json.dump(payload, f, indent=4)
                f.write('\n')

            if target_file.exists():
                try:
                    existing_stat = target_file.stat()
                    os.chmod(temp_path, stat.S_IMODE(existing_stat.st_mode))
                    if hasattr(os, "chown"):
                        try:
                            os.chown(temp_path, existing_stat.st_uid, existing_stat.st_gid)
                        except PermissionError:
                            # Best-effort owner/group preservation without requiring elevated privileges.
                            pass
                except OSError:
                    # Best-effort metadata preservation; data safety is prioritized.
                    pass

            os.replace(temp_path, target_file)
        except Exception:
            if temp_path and temp_path.exists():
                temp_path.unlink()
            raise

    try:
        with open(sub_item, 'r', encoding='utf-8') as f:
            # json5 natively supports comments and trailing commas (JSONC)
            new_settings = json5.load(f)

        if dest_file.exists():
            merged = merge_json_files(dest_file, new_settings, verbose=verbose and not tracker)
            if merged is not None:
                atomic_write_json(dest_file, merged)
                log("Merged:", "green")
                log("Note: comments/trailing commas are normalized when rewritten", "yellow")
            else:
                log("Skipped merge (preserved existing settings)", "yellow")
        else:
            shutil.copy2(sub_item, dest_file)
            log("Copied (no existing settings.json):", "blue")

    except Exception as e:
        log(f"Warning: Could not merge settings: {e}", "yellow")
        if not dest_file.exists():
            shutil.copy2(sub_item, dest_file)


def merge_json_files(existing_path: Path, new_content: Any, verbose: bool = False) -> dict[str, Any] | None:
    """Merge new JSON content into existing JSON file.

    Performs a polite deep merge where:
    - New keys are added
    - Existing keys are preserved (not overwritten) unless both values are dictionaries
    - Nested dictionaries are merged recursively only when both sides are dictionaries
    - Lists and other values are preserved from base if they exist

    Args:
        existing_path: Path to existing JSON file
        new_content: New JSON content to merge in
        verbose: Whether to print merge details

    Returns:
        Merged JSON content as dict, or None if the existing file should be left untouched.
    """
    # Load existing content first to have a safe fallback
    existing_content = None
    exists = existing_path.exists()

    if exists:
        try:
            with open(existing_path, 'r', encoding='utf-8') as f:
                # Handle comments (JSONC) natively with json5
                # Note: json5 handles BOM automatically
                existing_content = json5.load(f)
        except FileNotFoundError:
            # Handle race condition where file is deleted after exists() check
            exists = False
        except Exception as e:
            if verbose:
                console.print(f"[yellow]Warning: Could not read or parse existing JSON in {existing_path.name} ({e}).[/yellow]")
            # Skip merge to preserve existing file if unparseable or inaccessible (e.g. PermissionError)
            return None

    # Validate template content
    if not isinstance(new_content, dict):
        if verbose:
            console.print(f"[yellow]Warning: Template content for {existing_path.name} is not a dictionary. Preserving existing settings.[/yellow]")
        return None

    if not exists:
        return new_content

    # If existing content parsed but is not a dict, skip merge to avoid data loss
    if not isinstance(existing_content, dict):
        if verbose:
            console.print(f"[yellow]Warning: Existing JSON in {existing_path.name} is not an object. Skipping merge to avoid data loss.[/yellow]")
        return None

    def deep_merge_polite(base: dict[str, Any], update: dict[str, Any]) -> dict[str, Any]:
        """Recursively merge update dict into base dict, preserving base values."""
        result = base.copy()
        for key, value in update.items():
            if key not in result:
                # Add new key
                result[key] = value
            elif isinstance(result[key], dict) and isinstance(value, dict):
                # Recursively merge nested dictionaries
                result[key] = deep_merge_polite(result[key], value)
            else:
                # Key already exists and values are not both dicts; preserve existing value.
                # This ensures user settings aren't overwritten by template defaults.
                pass
        return result

    merged = deep_merge_polite(existing_content, new_content)

    # Detect if anything actually changed. If not, return None so the caller
    # can skip rewriting the file (preserving user's comments/formatting).
    if merged == existing_content:
        return None

    if verbose:
        console.print(f"[cyan]Merged JSON file:[/cyan] {existing_path.name}")

    return merged


def _display_project_path(project_root: Path, path: str | Path) -> str:
    """Return a stable POSIX-style display path for paths under a project."""
    path_obj = Path(path)
    try:
        rel_path = path_obj.relative_to(project_root) if path_obj.is_absolute() else path_obj
    except ValueError:
        try:
            rel_path = path_obj.resolve().relative_to(project_root.resolve())
        except (OSError, ValueError):
            return path_obj.as_posix()
    return rel_path.as_posix()
