package openrouter

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

type Client struct {
	BaseURL, APIKey, SiteURL, AppName string
	HTTP                              *http.Client
}

func (c *Client) do(ctx context.Context, method, path string, body any) (*http.Response, error) {
	var reader io.Reader
	if body != nil {
		b, err := json.Marshal(body)
		if err != nil {
			return nil, err
		}
		reader = bytes.NewReader(b)
	}
	req, err := http.NewRequestWithContext(ctx, method, strings.TrimRight(c.BaseURL, "/")+path, reader)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", "Bearer "+c.APIKey)
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	if c.SiteURL != "" {
		req.Header.Set("HTTP-Referer", c.SiteURL)
	}
	if c.AppName != "" {
		req.Header.Set("X-Title", c.AppName)
	}
	resp, err := c.HTTP.Do(req)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		defer resp.Body.Close()
		b, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
		return nil, fmt.Errorf("OpenRouter status %d: %s", resp.StatusCode, strings.TrimSpace(string(b)))
	}
	return resp, nil
}

type imageURL struct {
	URL string `json:"url"`
}
type contentPart struct {
	Type     string    `json:"type"`
	Text     string    `json:"text,omitempty"`
	ImageURL *imageURL `json:"image_url,omitempty"`
}
type message struct {
	Role    string `json:"role"`
	Content any    `json:"content"`
}

func (c *Client) Prompt(ctx context.Context, model, description, dataURL, system string) (string, error) {
	body := map[string]any{
		"model": model,
		"messages": []message{
			{Role: "system", Content: system},
			{Role: "user", Content: []contentPart{
				{Type: "text", Text: description},
				{Type: "image_url", ImageURL: &imageURL{URL: dataURL}},
			}},
		},
		"response_format": map[string]any{"type": "json_object"},
	}
	resp, err := c.do(ctx, http.MethodPost, "/chat/completions", body)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	var out struct {
		Choices []struct {
			Message struct {
				Content string `json:"content"`
			} `json:"message"`
		} `json:"choices"`
	}
	if err = json.NewDecoder(io.LimitReader(resp.Body, 2<<20)).Decode(&out); err != nil {
		return "", err
	}
	if len(out.Choices) == 0 {
		return "", fmt.Errorf("empty model response")
	}
	var result struct {
		VideoPrompt string `json:"video_prompt"`
	}
	content := out.Choices[0].Message.Content
	if err = json.Unmarshal([]byte(out.Choices[0].Message.Content), &result); err != nil {
		return "", fmt.Errorf("invalid JSON from model: %w\ncontent=%q", err, content)
	}
	if strings.TrimSpace(result.VideoPrompt) == "" {
		return "", fmt.Errorf("empty video prompt")
	}
	return result.VideoPrompt, nil
}

type VideoRequest struct {
	Model         string       `json:"model"`
	Prompt        string       `json:"prompt"`
	Duration      int          `json:"duration"`
	Resolution    string       `json:"resolution"`
	GenerateAudio bool         `json:"generate_audio"`
	FrameImages   []FrameImage `json:"frame_images"`
}
type FrameImage struct {
	Type      string   `json:"type"`
	ImageURL  imageURL `json:"image_url"`
	FrameType string   `json:"frame_type"`
}
type VideoJob struct {
	ID           string   `json:"id"`
	Status       string   `json:"status"`
	Error        string   `json:"error"`
	UnsignedURLs []string `json:"unsigned_urls"`
}

func NewImageURL(raw string) imageURL { return imageURL{URL: raw} }
func (c *Client) Submit(ctx context.Context, v VideoRequest) (VideoJob, error) {
	resp, err := c.do(ctx, http.MethodPost, "/videos", v)
	if err != nil {
		return VideoJob{}, err
	}
	defer resp.Body.Close()
	var job VideoJob
	err = json.NewDecoder(resp.Body).Decode(&job)
	return job, err
}
func (c *Client) Poll(ctx context.Context, id string) (VideoJob, error) {
	resp, err := c.do(ctx, http.MethodGet, "/videos/"+id, nil)
	if err != nil {
		return VideoJob{}, err
	}
	defer resp.Body.Close()
	var job VideoJob
	err = json.NewDecoder(resp.Body).Decode(&job)
	return job, err
}
func (c *Client) Content(ctx context.Context, id string) (*http.Response, error) {
	return c.do(ctx, http.MethodGet, "/videos/"+id+"/content?index=0", nil)
}