package openrouter

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

const defaultBaseURL = "https://openrouter.ai/api/v1"

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

type Option func(*Client)

func WithBaseURL(u string) Option {
	return func(c *Client) { c.baseURL = u }
}

func WithHTTPClient(hc *http.Client) Option {
	return func(c *Client) { c.httpClient = hc }
}

func NewClient(apiKey string, opts ...Option) *Client {
	c := &Client{
		apiKey:     apiKey,
		baseURL:    defaultBaseURL,
		httpClient: http.DefaultClient,
	}
	for _, o := range opts {
		o(c)
	}
	return c
}

func (c *Client) do(ctx context.Context, path string, reqBody, respBody any) error {
	data, err := json.Marshal(reqBody)
	if err != nil {
		return fmt.Errorf("openrouter: marshal request: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+path, bytes.NewReader(data))
	if err != nil {
		return fmt.Errorf("openrouter: build request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+c.apiKey)
	req.Header.Set("Content-Type", "application/json")

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("openrouter: send request: %w", err)
	}
	defer resp.Body.Close()

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

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("openrouter: HTTP %d: %s", resp.StatusCode, body)
	}

	if err := json.Unmarshal(body, respBody); err != nil {
		return fmt.Errorf("openrouter: unmarshal response: %w\nbody: %s", err, body)
	}
	return nil
}