from dataclasses import dataclass
from pathlib import Path

from .base import BaseGenerator


@dataclass
class TypeInfo:
    type: str
    imports: set[str]


@dataclass
class Field:
    name: str
    type: str
    description: str | None = None
    imports: set[str] | None = None
    optional: bool = False


@dataclass
class Model:
    name: str
    description: str
    fields: list[Field]


class PythonGenerator(BaseGenerator):
    TYPE_MAP = {
        "string": "str",
        "integer": "int",
        "number": "float",
        "boolean": "bool",
        "object": "dict",
        "float": "float",
    }

    FORMAT_MAP = {
        "int64": "int",
    }

    def generate(self, output_dir: str | Path, make_all: bool, schema_file: str | None):
        output_dir = Path(output_dir)
        output_dir.mkdir(
            parents=True,
            exist_ok=True,
        )

        generated = set()

        if make_all:
            for schema_file in self.schemas:
                self._generate_schema(
                    schema_file=schema_file,
                    output_dir=output_dir,
                    generated=generated,
                )
            return

        self._generate_schema(
            schema_file=schema_file,
            output_dir=output_dir,
            generated=generated,
        )

    def _generate_schema(
        self,
        schema_file: str,
        output_dir: Path,
        generated: set[str],
    ):
        # Already generated
        if schema_file in generated:
            return

        schema = self.schemas.get(schema_file)

        if schema is None:
            raise ValueError(f"Schema not found: {schema_file}")

        # Mark as generated before resolving dependencies.
        #
        # This also prevents infinite recursion if schemas
        # eventually reference each other.
        generated.add(schema_file)

        # First generate all referenced schemas.
        for ref in self._find_refs(schema):
            ref_file = self._ref_to_filename(ref)

            self._generate_schema(
                schema_file=ref_file,
                output_dir=output_dir,
                generated=generated,
            )

        # Now generate this schema itself.
        model = self._parse_model(schema)

        imports = self._collect_imports([model])

        template = self.env.get_template("python.jinja2")

        content = template.render(
            model=model,
            imports=sorted(imports),
        )

        module_name = self._schema_to_module(schema_file)

        output_file = output_dir / f"{module_name}.py"

        output_file.write_text(
            content,
            encoding="utf-8",
        )

    def _find_refs(self, schema: dict) -> list[str]:
        """
        Recursively find all $ref values inside a schema.
        """

        refs = []

        if "$ref" in schema:
            refs.append(schema["$ref"])

        for value in schema.values():
            if isinstance(value, dict):
                refs.extend(self._find_refs(value))

            elif isinstance(value, list):
                for item in value:
                    if isinstance(item, dict):
                        refs.extend(self._find_refs(item))

        return refs

    def _ref_to_filename(self, ref: str) -> str:
        """
        Convert:

            operation.schema.json

        into:

            operation.schema.json

        Also handles:

            ./operation.schema.json
        """

        return Path(ref).name

    def _parse_model(
        self,
        schema: dict,
    ) -> Model:

        name = schema["title"]

        fields = []

        required = set(schema.get("required", []))

        for (
            field_name,
            field_schema,
        ) in schema.get(
            "properties",
            {},
        ).items():

            type_info = self._resolve_type(field_schema)

            field_type = type_info.type

            if field_name not in required:
                field_type = f"{field_type} | None = None"

            fields.append(
                Field(
                    name=field_name,
                    type=field_type,
                    description=field_schema.get("description"),
                    imports=type_info.imports,
                    optional=field_name not in required,
                )
            )
        fields.sort(key=lambda field: field.optional)

        return Model(
            name=name,
            description=schema.get(
                "description",
                "",
            ),
            fields=fields,
        )

    def _resolve_type(
        self,
        schema: dict,
    ) -> TypeInfo:

        # $ref
        if "$ref" in schema:
            return self._resolve_ref(schema["$ref"])

        # array
        if schema.get("type") == "array":

            item = self._resolve_type(schema["items"])

            return TypeInfo(
                type=f"list[{item.type}]",
                imports=item.imports,
            )

        # format
        schema_format = schema.get("format")

        if schema_format in self.FORMAT_MAP:

            return TypeInfo(
                type=self.FORMAT_MAP[schema_format],
                imports=set(),
            )

        # primitive
        json_type = schema.get("type")

        if json_type in self.TYPE_MAP:

            return TypeInfo(
                type=self.TYPE_MAP[json_type],
                imports=set(),
            )

        raise ValueError(f"Unsupported schema: {schema}")

    def _resolve_ref(
        self,
        ref: str,
    ) -> TypeInfo:

        filename = self._ref_to_filename(ref)

        schema = self.schemas.get(filename)

        if schema is None:
            raise ValueError(f"Referenced schema not found: {filename}")

        model_name = schema["title"]

        module_name = self._schema_to_module(filename)

        return TypeInfo(
            type=model_name,
            imports={f"from .{module_name} import {model_name}"},
        )

    def _schema_to_module(
        self,
        filename: str,
    ) -> str:

        return filename.removesuffix(".schema.json").replace("-", "_")

    def _collect_imports(
        self,
        models: list[Model],
    ) -> set[str]:

        imports = set()

        for model in models:
            for field in model.fields:
                if field.imports:
                    imports.update(field.imports)

        return imports