#!/usr/bin/env python3
"""Reject UI, Windows, SQLite, and app-layer imports from the core module."""

import json
import os
import pathlib
import subprocess
import sys


FORBIDDEN_IMPORT_PREFIXES = (
    "gioui.org",
    "golang.org/x/sys/windows",
    "github.com/mattn/go-sqlite3",
    "modernc.org/sqlite",
    "softbox.local/app-modern",
    "softbox.local/app-win7",
)


def is_forbidden(import_path):
    return any(
        import_path == prefix or import_path.startswith(prefix + "/")
        for prefix in FORBIDDEN_IMPORT_PREFIXES
    )


def decode_json_stream(text):
    decoder = json.JSONDecoder()
    index = 0
    while index < len(text):
        while index < len(text) and text[index].isspace():
            index += 1
        if index >= len(text):
            return
        value, index = decoder.raw_decode(text, index)
        yield value


def list_core_packages(repo_root):
    environment = os.environ.copy()
    environment["GOWORK"] = "off"
    result = subprocess.run(
        ["go", "list", "-json", "./..."],
        cwd=str(repo_root / "core"),
        env=environment,
        check=False,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        universal_newlines=True,
    )
    if result.returncode != 0:
        print(result.stderr, file=sys.stderr, end="")
        raise SystemExit(result.returncode)
    return list(decode_json_stream(result.stdout))


def run_self_test():
    cases = (
        ("gioui.org/layout", True),
        ("golang.org/x/sys/windows/registry", True),
        ("modernc.org/sqlite/lib", True),
        ("softbox.local/app-modern/ui/gio", True),
        ("context", False),
        ("crypto/sha256", False),
    )
    failures = [
        import_path
        for import_path, expected in cases
        if is_forbidden(import_path) != expected
    ]
    if failures:
        print(
            "ERROR: boundary matcher self-test failed for {}".format(
                ", ".join(failures)
            ),
            file=sys.stderr,
        )
        raise SystemExit(1)
    print("core boundary matcher self-test passed.")


def main():
    if sys.argv[1:] == ["--self-test"]:
        run_self_test()
        return
    if len(sys.argv) != 1:
        print(
            "usage: python scripts/check_core_boundaries.py [--self-test]",
            file=sys.stderr,
        )
        raise SystemExit(2)

    repo_root = pathlib.Path(__file__).resolve().parents[1]
    violations = []

    for package in list_core_packages(repo_root):
        imports = set(package.get("Imports", []))
        imports.update(package.get("TestImports", []))
        imports.update(package.get("XTestImports", []))
        for import_path in sorted(imports):
            if is_forbidden(import_path):
                violations.append((package["ImportPath"], import_path))

    if violations:
        for package, import_path in violations:
            print(
                "ERROR: {} imports forbidden dependency {}".format(
                    package, import_path
                ),
                file=sys.stderr,
            )
        raise SystemExit(1)

    print(
        "core boundary check passed: {} forbidden prefixes absent.".format(
            len(FORBIDDEN_IMPORT_PREFIXES)
        )
    )


if __name__ == "__main__":
    main()