#!/usr/bin/env python3
from __future__ import annotations

import ast
import json
import os
import re
from dataclasses import dataclass
from pathlib import Path

META_ROOT = Path(__file__).resolve().parents[2]
CORE_ROOT = Path(os.environ.get("GOVOPLAN_CORE_ROOT", META_ROOT.parent / "govoplan-core")).resolve()
REPOS_ROOT = Path(os.environ.get("GOVOPLAN_REPOS_ROOT", CORE_ROOT.parent)).resolve()


def _discover_python_repos(
    repos_root: Path = REPOS_ROOT,
) -> tuple[dict[str, Path], dict[str, str], tuple[str, ...]]:
    repos: dict[str, Path] = {}
    prefixes: dict[str, str] = {}
    errors: list[str] = []
    for repo_root in sorted(repos_root.glob("govoplan*")):
        source_root = repo_root / "src"
        if not source_root.is_dir():
            continue
        packages = sorted(
            path
            for path in source_root.glob("govoplan_*")
            if path.is_dir() and (path / "__init__.py").is_file()
        )
        if len(packages) != 1:
            discovered = ", ".join(path.name for path in packages) or "none"
            errors.append(
                f"{repo_root.name}: expected exactly one importable govoplan_* package "
                f"under {source_root}, found {len(packages)} ({discovered})"
            )
            continue
        owner = repo_root.name
        prefix = packages[0].name
        duplicate_owner = next(
            (candidate_owner for candidate_owner, candidate_prefix in prefixes.items() if candidate_prefix == prefix),
            None,
        )
        if duplicate_owner is not None:
            errors.append(
                f"{owner}: import package {prefix!r} is already owned by {duplicate_owner}; "
                "Python package ownership must be unique"
            )
            continue
        repos[owner] = packages[0]
        prefixes[owner] = prefix
    return repos, prefixes, tuple(errors)


def _discover_webui_repos(
    repos_root: Path = REPOS_ROOT,
) -> tuple[dict[str, Path], dict[str, str], tuple[str, ...]]:
    repos: dict[str, Path] = {}
    packages: dict[str, str] = {}
    errors: list[str] = []
    for repo_root in sorted(repos_root.glob("govoplan*")):
        webui_root = repo_root / "webui"
        if not webui_root.is_dir():
            continue
        package_path = webui_root / "package.json"
        if not package_path.is_file():
            errors.append(f"{repo_root.name}: WebUI directory has no package.json: {package_path}")
            continue
        try:
            payload = json.loads(package_path.read_text(encoding="utf-8"))
        except json.JSONDecodeError as exc:
            errors.append(f"{repo_root.name}: invalid {package_path}: {exc}")
            continue
        package_name = payload.get("name") if isinstance(payload, dict) else None
        if not isinstance(package_name, str) or not package_name:
            errors.append(f"{repo_root.name}: {package_path} must declare a non-empty package name")
            continue
        owner = repo_root.name
        duplicate_owner = next(
            (candidate_owner for candidate_owner, candidate_package in packages.items() if candidate_package == package_name),
            None,
        )
        if duplicate_owner is not None:
            errors.append(
                f"{owner}: WebUI package {package_name!r} is already owned by {duplicate_owner}; "
                "WebUI package ownership must be unique"
            )
            continue
        repos[owner] = webui_root
        packages[owner] = package_name
    return repos, packages, tuple(errors)


REPOS, PREFIXES, PYTHON_DISCOVERY_ERRORS = _discover_python_repos()
WEBUI_REPOS, WEBUI_PACKAGES, WEBUI_DISCOVERY_ERRORS = _discover_webui_repos()
CORE_OWNER = CORE_ROOT.name
WEBUI_IMPORT_RE = re.compile(
    r"(?:from\s+|import\s*\(\s*|require\s*\(\s*|export\s+[^;]*?\s+from\s+)"
    r"[\"'](?P<package>@govoplan/[a-z0-9_-]+-webui)(?:/[A-Za-z0-9_./-]+)?[\"']"
    r"|import\s+[\"'](?P<side_effect_package>@govoplan/[a-z0-9_-]+-webui)(?:/[A-Za-z0-9_./-]+)?[\"']"
)


@dataclass(frozen=True)
class AllowlistedImport:
    owner: str
    relative_path: str
    imported_owner: str
    reason: str


# Transitional exceptions. This should remain empty; add entries only with a
# dated removal plan and a capability/API contract issue.
ALLOWLIST: tuple[AllowlistedImport, ...] = ()
ALLOWLIST_KEYS = {(item.owner, item.relative_path, item.imported_owner) for item in ALLOWLIST}


@dataclass(frozen=True)
class Violation:
    kind: str
    owner: str
    path: Path
    lineno: int
    imported: str
    imported_owner: str


def _import_owner(module_name: str) -> str | None:
    for owner, prefix in PREFIXES.items():
        if module_name == prefix or module_name.startswith(f"{prefix}."):
            return owner
    return None


def _imports(path: Path) -> list[tuple[int, str]]:
    tree = ast.parse(path.read_text(), filename=str(path))
    result: list[tuple[int, str]] = []
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            for alias in node.names:
                result.append((node.lineno, alias.name))
        elif isinstance(node, ast.ImportFrom) and node.module:
            result.append((node.lineno, node.module))
    return result


def _relative(owner: str, path: Path) -> str:
    return path.relative_to(REPOS[owner]).as_posix()


def _allowed(owner: str, path: Path, imported_owner: str) -> bool:
    return (owner, _relative(owner, path), imported_owner) in ALLOWLIST_KEYS


def _violations() -> list[Violation]:
    violations: list[Violation] = []
    for owner, root in REPOS.items():
        if not root.exists():
            continue
        for path in root.rglob("*.py"):
            if "__pycache__" in path.parts:
                continue
            for lineno, imported in _imports(path):
                imported_owner = _import_owner(imported)
                if imported_owner is None or imported_owner == owner:
                    continue
                if imported_owner != CORE_OWNER and not _allowed(owner, path, imported_owner):
                    violations.append(Violation("python", owner, path, lineno, imported, imported_owner))
    violations.extend(_webui_violations())
    return violations


def _webui_package_owner(package_name: str) -> str | None:
    for owner, package in WEBUI_PACKAGES.items():
        if package_name == package:
            return owner
    return None


def _webui_source_files(root: Path) -> list[Path]:
    source_root = root / "src"
    if not source_root.exists():
        return []
    return [
        path
        for path in source_root.rglob("*")
        if path.suffix in {".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs"}
        and "node_modules" not in path.parts
        and "dist" not in path.parts
    ]


def _webui_dependency_fields(payload: object) -> dict[str, object]:
    if not isinstance(payload, dict):
        return {}
    result: dict[str, object] = {}
    for key in ("dependencies", "devDependencies", "peerDependencies", "optionalDependencies"):
        value = payload.get(key)
        if isinstance(value, dict):
            result.update(value)
    return result


def _webui_package_json_violations(owner: str, root: Path) -> list[Violation]:
    violations: list[Violation] = []
    package_paths = [root / "package.json"]
    if root.name == "webui":
        package_paths.append(root.parent / "package.json")
    for package_path in tuple(dict.fromkeys(package_paths)):
        if not package_path.exists():
            continue
        try:
            payload = json.loads(package_path.read_text(encoding="utf-8"))
        except json.JSONDecodeError as exc:
            return [Violation("webui-package", owner, package_path, exc.lineno, "invalid package.json", owner)]
        for package_name in _webui_dependency_fields(payload):
            imported_owner = _webui_package_owner(str(package_name))
            if imported_owner is None or imported_owner == owner:
                continue
            # The core WebUI package is also the development composition host;
            # package declarations make independently built module frontends
            # available to Vite without authorizing source-level imports.
            if owner == CORE_OWNER:
                continue
            if imported_owner != CORE_OWNER:
                violations.append(Violation("webui-package", owner, package_path, 1, str(package_name), imported_owner))
    return violations


def _webui_source_violations(owner: str, root: Path) -> list[Violation]:
    violations: list[Violation] = []
    for path in _webui_source_files(root):
        text = path.read_text(encoding="utf-8")
        for match in WEBUI_IMPORT_RE.finditer(text):
            package_name = match.group("package") or match.group("side_effect_package")
            imported_owner = _webui_package_owner(package_name)
            if imported_owner is None or imported_owner == owner:
                continue
            lineno = text.count("\n", 0, match.start()) + 1
            if imported_owner != CORE_OWNER:
                violations.append(Violation("webui-source", owner, path, lineno, package_name, imported_owner))
    return violations


def _webui_violations() -> list[Violation]:
    violations: list[Violation] = []
    for owner, root in WEBUI_REPOS.items():
        if not root.exists():
            continue
        violations.extend(_webui_package_json_violations(owner, root))
        violations.extend(_webui_source_violations(owner, root))
    return violations


def main() -> int:
    discovery_errors = (*PYTHON_DISCOVERY_ERRORS, *WEBUI_DISCOVERY_ERRORS)
    if discovery_errors:
        print("Dependency boundary discovery errors:")
        for error in discovery_errors:
            print(f"- {error}")
        print("\nThe boundary scan is incomplete; fix package discovery before accepting this gate.")
        return 1

    violations = _violations()
    if not violations:
        print(
            "Dependency boundary check passed "
            f"({len(REPOS)} Python repos, {len(WEBUI_REPOS)} WebUI repos, "
            f"{len(ALLOWLIST)} transitional exceptions tracked)"
        )
        return 0

    print("Dependency boundary violations:")
    for item in violations:
        print(
            f"- {item.path}:{item.lineno}: {item.owner} {item.kind} imports {item.imported} "
            f"({item.imported_owner}); use kernel capability/API/event contracts instead"
        )
    print("\nIf this is unavoidable transitional debt, add a reasoned ALLOWLIST entry.")
    return 1


if __name__ == "__main__":
    raise SystemExit(main())