package rudder

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
)

type transport struct {
	baseURL    string
	apiKey     string
	projectID  string
	httpClient *http.Client
}

func (t *transport) do(ctx context.Context, method, path string, query url.Values, body any, out any) error {
	endpoint := strings.TrimSuffix(t.baseURL, "/") + "/game/v1/projects/" + t.projectID + path
	if len(query) > 0 {
		endpoint += "?" + query.Encode()
	}

	var reader io.Reader
	if body != nil {
		data, err := json.Marshal(body)
		if err != nil {
			return fmt.Errorf("rudder: encode request body: %w", err)
		}
		reader = bytes.NewReader(data)
	}

	req, err := http.NewRequestWithContext(ctx, method, endpoint, reader)
	if err != nil {
		return fmt.Errorf("rudder: build request: %w", err)
	}
	req.Header.Set("X-API-Key", t.apiKey)
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}

	resp, err := t.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("rudder: %s %s: %w", method, path, err)
	}
	defer resp.Body.Close()

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("rudder: read response body: %w", err)
	}

	if resp.StatusCode >= 400 {
		apiErr := &APIError{Status: resp.StatusCode}
		var payload struct {
			Error     string `json:"error"`
			Code      string `json:"code"`
			RequestID string `json:"requestId"`
		}
		if json.Unmarshal(data, &payload) == nil {
			apiErr.Code = payload.Code
			apiErr.Message = payload.Error
			apiErr.RequestID = payload.RequestID
		}
		if apiErr.Message == "" {
			apiErr.Message = http.StatusText(resp.StatusCode)
		}
		return apiErr
	}

	if out == nil || len(data) == 0 {
		return nil
	}
	if err := json.Unmarshal(data, out); err != nil {
		return fmt.Errorf("rudder: decode response: %w", err)
	}
	return nil
}