"""Read-only, bounded access to the explicitly configured project workspace."""

from __future__ import annotations

import os
import re
from pathlib import Path

ALLOWED_SUFFIXES = {
    ".py", ".dart", ".md", ".txt", ".json", ".yaml", ".yml", ".toml",
    ".html", ".css", ".js", ".ts", ".tsx", ".jsx", ".sh", ".ps1",
}
IGNORED_PARTS = {
    ".git", ".venv", ".dart_tool", ".video-lab", "build", "node_modules",
    "__pycache__", ".idea", ".vscode",
}
MAX_FILE_BYTES = 256 * 1024
MAX_SCAN_FILES = 500


def configured_root() -> Path | None:
    value = os.getenv("SOVEREIGNAI_WORKSPACE")
    if not value:
        return None
    root = Path(value).expanduser().resolve()
    return root if root.is_dir() else None


def relative_file(root: Path, relative_path: str) -> Path:
    candidate = (root / relative_path).resolve(strict=True)
    try:
        candidate.relative_to(root)
    except ValueError as exc:
        raise ValueError("المسار المطلوب خارج مساحة العمل.") from exc
    if not candidate.is_file() or candidate.suffix.lower() not in ALLOWED_SUFFIXES:
        raise ValueError("هذا النوع من الملفات غير مسموح بقراءته.")
    if any(
        part in IGNORED_PARTS or part.startswith(".")
        for part in candidate.relative_to(root).parts
    ):
        raise ValueError("قراءة الملفات المخفية أو المستثناة غير مسموحة.")
    if candidate.stat().st_size > MAX_FILE_BYTES:
        raise ValueError("الملف أكبر من الحد المسموح للقراءة (256 كيلوبايت).")
    return candidate


def list_text_files(root: Path) -> list[Path]:
    files: list[Path] = []
    for current, directories, filenames in os.walk(root, followlinks=False):
        directories[:] = [
            name for name in directories
            if name not in IGNORED_PARTS and not name.startswith(".")
        ]
        for filename in filenames:
            path = Path(current) / filename
            if path.suffix.lower() not in ALLOWED_SUFFIXES:
                continue
            try:
                relative_file(root, path.relative_to(root).as_posix())
            except (OSError, ValueError):
                continue
            files.append(path)
            if len(files) >= MAX_SCAN_FILES:
                return files
    return files


def retrieve(task: str, root: Path, limit: int = 3) -> list[tuple[str, str]]:
    terms = {
        term.casefold()
        for term in re.findall(r"[\w\u0600-\u06ff]{3,}", task)
        if term.casefold() not in {
            "the", "and", "for", "with", "this", "that", "من", "على", "في", "عن",
            "كيف", "شو", "ما", "ماذا", "هذا", "هذه", "التي", "الذي", "اشرح", "دور",
            "ملف", "ملفات", "اذكر", "المستخدمة", "المستخدم", "المشروع", "التفسير",
        }
    }
    mentioned_paths = {
        match.replace("\\", "/").casefold()
        for match in re.findall(
            r"(?:[\w.-]+[\\/])+[\w.-]+\.(?:py|dart|md|txt|json|ya?ml|toml|html|css|js|ts|tsx|jsx|sh|ps1)",
            task,
            flags=re.IGNORECASE,
        )
    }
    ranked: list[tuple[int, str, str]] = []
    for path in list_text_files(root):
        try:
            text = path.read_text(encoding="utf-8", errors="replace")
        except OSError:
            continue
        if not text.strip():
            continue
        lowered = text.casefold()
        words = re.findall(r"[\w\u0600-\u06ff]+", lowered)
        score = sum(words.count(term) for term in terms)
        relative = path.relative_to(root).as_posix()
        if relative.casefold() in mentioned_paths:
            score += 100_000
        if score:
            ranked.append((score, relative, text[:1800]))
    ranked.sort(key=lambda item: (-item[0], item[1]))
    return [(relative, content) for _, relative, content in ranked[:limit]]