"""Generate a Go package from thrift-files/meowment-network."""

from __future__ import annotations

import argparse
import os
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path
from typing import Iterable, Sequence


REPO_ROOT = Path(__file__).resolve().parents[2]
DEFAULT_SOURCE_DIR = REPO_ROOT / "thrift-files" / "meowment-network"
DEFAULT_OUTPUT_DIR = REPO_ROOT / "compiled_output" / "golang" / "meowmentnet"
DEFAULT_PACKAGE_NAME = "meowmentnet"
DEFAULT_THRIFT_IMPORT = "github.com/apache/thrift/lib/go/thrift"


class ToolError(RuntimeError):
    pass


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Generate a Go package from meowment-network thrift files.",
    )
    parser.add_argument(
        "--source-dir",
        type=Path,
        default=DEFAULT_SOURCE_DIR,
        help="Directory containing .thrift files.",
    )
    parser.add_argument(
        "--output-dir",
        type=Path,
        default=DEFAULT_OUTPUT_DIR,
        help="Destination directory of the generated Go package.",
    )
    parser.add_argument(
        "--package-name",
        default=DEFAULT_PACKAGE_NAME,
        help="Generated Go package name.",
    )
    parser.add_argument(
        "--compiler",
        type=Path,
        help="Explicit thrift compiler executable path.",
    )
    parser.add_argument(
        "--package-prefix",
        default="",
        help="Optional value passed to go:package_prefix=...",
    )
    parser.add_argument(
        "--thrift-import",
        default=DEFAULT_THRIFT_IMPORT,
        help="Import path of the Go thrift runtime.",
    )
    parser.add_argument(
        "--module",
        default="",
        help="If set, write a go.mod file with this module path.",
    )
    parser.add_argument(
        "--no-clean",
        action="store_true",
        help="Do not delete the existing output directory before copying files.",
    )
    parser.add_argument(
        "--skip-gofmt",
        action="store_true",
        help="Do not run gofmt after generation.",
    )
    parser.add_argument(
        "--skip-go-mod-tidy",
        action="store_true",
        help="Do not run go mod tidy after writing go.mod.",
    )
    return parser.parse_args()


def candidate_compilers(explicit: Path | None) -> Iterable[Path]:
    seen: set[str] = set()

    def emit(path: Path | None) -> Iterable[Path]:
        if path is None:
            return ()
        resolved = str(path)
        if resolved in seen:
            return ()
        seen.add(resolved)
        return (path,)

    if explicit is not None:
        yield from emit(explicit)

    env_compiler = Path(os.environ["THRIFT_COMPILER"]) if "THRIFT_COMPILER" in os.environ else None
    yield from emit(env_compiler)
    yield from emit(REPO_ROOT / "compiler" / "exe" / "thrift-go.exe")

    system_compiler = shutil.which("thrift")
    if system_compiler:
        yield from emit(Path(system_compiler))


def probe_compiler(executable: Path) -> bool:
    try:
        completed = subprocess.run(
            [str(executable), "-version"],
            check=False,
            capture_output=True,
            text=True,
            timeout=10,
        )
    except OSError:
        return False
    except subprocess.TimeoutExpired:
        return False
    return completed.returncode == 0


def resolve_compiler(explicit: Path | None) -> Path:
    for compiler in candidate_compilers(explicit):
        if probe_compiler(compiler):
            return compiler
    raise ToolError(
        "No working thrift compiler was found. Use --compiler or set THRIFT_COMPILER."
    )


def find_thrift_files(source_dir: Path) -> list[Path]:
    if not source_dir.exists():
        raise ToolError(f"Source directory does not exist: {source_dir}")
    thrift_files = sorted(source_dir.glob("*.thrift"))
    if not thrift_files:
        raise ToolError(f"No .thrift files were found in: {source_dir}")
    return thrift_files


def build_generator_option(args: argparse.Namespace) -> str:
    options = [f"package={args.package_name}"]
    options.append("ignore_initialisms")
    if args.package_prefix:
        options.append(f"package_prefix={normalize_package_prefix(args.package_prefix)}")
    if args.thrift_import:
        options.append(f"thrift_import={args.thrift_import}")
    options.append("skip_remote")
    return "go:" + ",".join(options)


def normalize_package_prefix(prefix: str) -> str:
    normalized = prefix.strip()
    if not normalized:
        return normalized
    return normalized if normalized.endswith("/") else normalized + "/"


def run_command(command: Sequence[str], cwd: Path) -> None:
    completed = subprocess.run(
        list(command),
        cwd=str(cwd),
        check=False,
        capture_output=True,
        text=True,
    )
    if completed.returncode == 0:
        return

    stdout = completed.stdout.strip()
    stderr = completed.stderr.strip()
    details = "\n".join(part for part in (stdout, stderr) if part)
    if not details:
        details = "The command exited with a non-zero status and produced no output."
    raise ToolError(details)


def generate_go_sources(
    compiler: Path,
    source_dir: Path,
    thrift_files: Sequence[Path],
    package_name: str,
    generator_option: str,
    staging_root: Path,
) -> Path:
    for thrift_file in thrift_files:
        command = [
            str(compiler),
            "-o",
            str(staging_root),
            "-strict",
            "--gen",
            generator_option,
            str(thrift_file),
        ]
        try:
            run_command(command, cwd=source_dir)
        except ToolError as exc:
            raise ToolError(f"Failed to generate {thrift_file.name}:\n{exc}") from exc

    package_dir = staging_root / "gen-go" / package_name
    if not package_dir.exists():
        raise ToolError(f"Generated package directory not found: {package_dir}")

    return package_dir


def write_go_mod(output_dir: Path, module_name: str) -> None:
    go_mod = output_dir / "go.mod"
    go_mod.write_text(
        "\n".join(
            [
                f"module {module_name}",
                "",
                "go 1.22",
                "",
                "require github.com/apache/thrift v0.22.0",
                "",
            ]
        ),
        encoding="utf-8",
    )


def copy_output(staged_package_dir: Path, output_dir: Path, clean: bool) -> None:
    if clean and output_dir.exists():
        shutil.rmtree(output_dir)
    output_dir.parent.mkdir(parents=True, exist_ok=True)
    shutil.copytree(staged_package_dir, output_dir, dirs_exist_ok=not clean)


def run_gofmt(output_dir: Path) -> None:
    gofmt = shutil.which("gofmt")
    if not gofmt:
        print("[warn] gofmt was not found in PATH. Skipping formatting.")
        return

    go_files = sorted(output_dir.glob("*.go"))
    if not go_files:
        return

    for go_file in go_files:
        run_command([gofmt, "-w", str(go_file)], cwd=output_dir)


def run_go_mod_tidy(output_dir: Path) -> None:
    go = shutil.which("go")
    if not go:
        print("[warn] go was not found in PATH. Skipping go mod tidy.")
        return

    run_command([go, "mod", "tidy"], cwd=output_dir)


def validate_args(args: argparse.Namespace) -> None:
    if not args.package_name.strip():
        raise ToolError("--package-name cannot be empty.")


def main() -> int:
    args = parse_args()
    try:
        validate_args(args)
        source_dir = args.source_dir.resolve()
        output_dir = args.output_dir.resolve()
        thrift_files = find_thrift_files(source_dir)
        compiler = resolve_compiler(args.compiler.resolve() if args.compiler else None)
        generator_option = build_generator_option(args)
        with tempfile.TemporaryDirectory(prefix="thrift_go_") as tmp_dir:
            staged_package_dir = generate_go_sources(
                compiler=compiler,
                source_dir=source_dir,
                thrift_files=thrift_files,
                package_name=args.package_name,
                generator_option=generator_option,
                staging_root=Path(tmp_dir),
            )
            copy_output(staged_package_dir, output_dir, clean=not args.no_clean)
        if args.module:
            write_go_mod(output_dir, args.module)
            if not args.skip_go_mod_tidy:
                run_go_mod_tidy(output_dir)
        if not args.skip_gofmt:
            run_gofmt(output_dir)

        print(f"Compiler: {compiler}")
        print(f"Source directory: {source_dir}")
        print(f"Output directory: {output_dir}")
        print(f"Package name: {args.package_name}")
        print(f"Thrift files: {len(thrift_files)}")
        if args.module:
            print(f"go.mod: {args.module}")
        return 0
    except ToolError as exc:
        print(f"[error] {exc}", file=sys.stderr)
        return 1


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