import httpx

from .schemas import (
    EndpointInfo,
    Parameter,
    RequestBody,
    Response,
)

JSON_TYPE_MAP = {
    "string": "string",
    "integer": "integer",
    "number": "number",
    "boolean": "boolean",
    "array": "array",
    "object": "object",
}


def _resolve_ref(spec: dict, ref: str) -> dict:
    """Resolve a $ref pointer like '#/components/schemas/MyModel'."""
    parts = ref.lstrip("#/").split("/")
    node = spec
    for part in parts:
        node = node[part]
    return node


def _get_type(schema: dict, spec: dict) -> str:
    if "$ref" in schema:
        schema = _resolve_ref(spec, schema["$ref"])
    if "type" in schema:
        return JSON_TYPE_MAP.get(schema["type"], schema["type"])
    if "anyOf" in schema:
        types = [_get_type(s, spec) for s in schema["anyOf"] if s.get("type") != "null"]
        return types[0] if len(types) == 1 else " | ".join(types)
    return "unknown"


def _extract_fields(schema: dict, spec: dict) -> dict[str, str]:
    """Extract field_name -> type from an object schema."""
    if "$ref" in schema:
        schema = _resolve_ref(spec, schema["$ref"])
    properties = schema.get("properties", {})
    return {name: _get_type(prop, spec) for name, prop in properties.items()}


def _parse_parameters(params: list[dict], spec: dict) -> list[Parameter]:
    result = []
    for p in params:
        if "$ref" in p:
            p = _resolve_ref(spec, p["$ref"])
        schema = p.get("schema", {})
        result.append(
            Parameter(
                name=p["name"],
                location=p["in"],
                type=_get_type(schema, spec),
                required=p.get("required", False),
                description=p.get("description"),
            )
        )
    return result


def _parse_request_body(body: dict | None, spec: dict) -> RequestBody | None:
    if not body:
        return None
    if "$ref" in body:
        body = _resolve_ref(spec, body["$ref"])
    content = body.get("content", {})
    for content_type, media in content.items():
        schema = media.get("schema", {})
        fields = _extract_fields(schema, spec)
        return RequestBody(content_type=content_type, fields=fields)
    return None


def _parse_responses(responses: dict, spec: dict) -> list[Response]:
    result = []
    for status_code, resp in responses.items():
        if "$ref" in resp:
            resp = _resolve_ref(spec, resp["$ref"])
        content = resp.get("content", {})
        if content:
            for content_type, media in content.items():
                schema = media.get("schema", {})
                fields = _extract_fields(schema, spec)
                result.append(
                    Response(
                        status_code=str(status_code),
                        description=resp.get("description"),
                        content_type=content_type,
                        fields=fields,
                    )
                )
                break
        else:
            result.append(
                Response(
                    status_code=str(status_code),
                    description=resp.get("description"),
                    fields={},
                )
            )
    return result


def parse_endpoint(spec: dict, path: str, method: str, operation: dict) -> EndpointInfo:
    return EndpointInfo(
        path=path,
        method=method.upper(),
        summary=operation.get("summary"),
        description=operation.get("description"),
        operation_id=operation.get("operationId"),
        parameters=_parse_parameters(operation.get("parameters", []), spec),
        request_body=_parse_request_body(operation.get("requestBody"), spec),
        responses=_parse_responses(operation.get("responses", {}), spec),
    )


def _normalize_path(p: str) -> str:
    """Strip trailing slashes for consistent comparison, but keep root '/'."""
    return p.rstrip("/") or "/"


async def fetch_and_parse(spec_url: str, path: str | None = None, method: str | None = None) -> list[EndpointInfo]:
    async with httpx.AsyncClient() as client:
        resp = await client.get(str(spec_url), follow_redirects=True)
        resp.raise_for_status()
        spec = resp.json()

    normalized_path = _normalize_path(path) if path else None
    endpoints: list[EndpointInfo] = []

    for ep_path, methods in spec.get("paths", {}).items():
        if normalized_path and _normalize_path(ep_path) != normalized_path:
            continue
        for ep_method, operation in methods.items():
            if ep_method in ("parameters", "summary", "description", "servers"):
                continue
            if method and ep_method.upper() != method.upper():
                continue
            endpoints.append(parse_endpoint(spec, ep_path, ep_method, operation))

    return endpoints