import json
import os
from io import StringIO
from pathlib import Path

from django.conf import settings
from django.core.management import BaseCommand, CommandError, call_command


class Command(BaseCommand):
    help = "生成供 Swagger UI 和 ReDoc 使用的静态 Swagger JSON"

    def add_arguments(self, parser):
        parser.add_argument(
            "--output",
            help="输出路径，默认使用 settings.SWAGGER_SCHEMA_PATH",
        )
        parser.add_argument(
            "--url",
            help="文档中的 API 根地址，默认使用 settings.BASE_URL",
        )

    def handle(self, *args, **options):
        target = Path(options["output"] or settings.SWAGGER_SCHEMA_PATH)
        if not target.is_absolute():
            target = Path(settings.BASE_DIR) / target
        target = target.resolve()
        target.parent.mkdir(parents=True, exist_ok=True)

        temporary = target.with_name(f".{target.name}.{os.getpid()}.tmp")
        try:
            output = StringIO()
            call_command(
                "generate_swagger",
                "-",
                format="json",
                api_url=options["url"] or settings.BASE_URL,
                mock=True,
                verbosity=0,
                stdout=output,
            )
            content = output.getvalue()
            schema = json.loads(content)
            if schema.get("swagger") != "2.0" or not schema.get("paths"):
                raise CommandError("生成的 Swagger 文档缺少版本或接口路径")

            content = json.dumps(
                schema,
                ensure_ascii=False,
                separators=(",", ":"),
            )
            temporary.write_text(content, encoding="utf-8")
            os.replace(temporary, target)
        except Exception as exc:
            if isinstance(exc, CommandError):
                raise
            raise CommandError(f"生成 Swagger 文档失败：{exc}") from exc
        finally:
            temporary.unlink(missing_ok=True)

        operation_count = sum(
            method.lower() in {"get", "post", "put", "patch", "delete"}
            for path in schema["paths"].values()
            for method in path
        )
        self.stdout.write(
            self.style.SUCCESS(
                f"Swagger文档已生成：{target} "
                f"（{len(schema['paths'])}个路径，{operation_count}个操作）"
            )
        )