package main

import (
	"fmt"
	"github.com/gofiber/fiber/v3/client"
	"net/url"
	"regexp"
	"strconv"
	"strings"
)

var headers = map[string][]string{
	"Accept":       {"application/json"},
	"Content-Type": {"application/json"},
	"User-Agent":   {"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36"},
	"Host":         {"api.bilibili.com"},
}

type Client struct {
	cli *client.Client
}

func NewClient(sessData string) *Client {
	return &Client{
		cli: client.New().AddHeaders(headers).SetCookie("SESSDATA", sessData),
	}
}

func (c *Client) GetSubtitles(url string) (string, error) {
	vid, page, err := parseBilibiliUrl(url)
	if err != nil {
		return "", err
	}
	data, err := c.callView(vid)
	if err != nil {
		return "", err
	}
	var aid, cid = data.Data.Stat.Aid, 0
	for _, p := range data.Data.Pages {
		if p.Page == page {
			cid = p.Cid
		}
	}
	player, err := c.callPlayer(aid, cid)
	if err != nil {
		return "", err
	}
	subTitlesUrl := ""
	for _, sub := range player.Data.Subtitle.Subtitles {
		if sub.SubtitleUrl != "" {
			subTitlesUrl = fmt.Sprintf("https:%s", sub.SubtitleUrl)
			break
		}
	}
	if subTitlesUrl == "" {
		return "", fmt.Errorf("没有找到字幕")
	}
	subtitles, err := c.callSubtitles(subTitlesUrl)
	if err != nil {
		return "", err
	}
	var subtitlesList = make([]string, 0, len(subtitles.Body))
	for _, sub := range subtitles.Body {
		subtitlesList = append(subtitlesList, sub.Content)
	}
	return strings.Join(subtitlesList, "\n"), nil
}

func (c *Client) callView(vid string) (data Response[ViewResponseData], err error) {
	var r = c.cli.R()
	if strings.HasPrefix(vid, "av") {
		r.AddParam("aid", vid[2:])
	} else {
		r.AddParam("bvid", vid)
	}
	resp, err := r.Get("https://api.bilibili.com/x/web-interface/view")
	if err != nil {
		return data, fmt.Errorf("请求 %s 出错：%v", r.URL(), err)
	}
	err = resp.JSON(&data)
	return data, err
}

func (c *Client) callPlayer(aid, cid int) (data Response[PlayerResponseData], err error) {
	var r = c.cli.R()
	r.AddParam("aid", strconv.Itoa(aid))
	r.AddParam("cid", strconv.Itoa(cid))

	resp, err := r.Get("https://api.bilibili.com/x/player/v2")
	if err != nil {
		return data, fmt.Errorf("请求 %s 出错：%v", r.URL(), err)
	}
	err = resp.JSON(&data)
	return data, err
}

func (c *Client) callSubtitles(url string) (data SubtitlesResponse, err error) {
	var r = c.cli.R()
	resp, err := r.Get(url)
	if err != nil {
		return data, fmt.Errorf("请求 %s 出错：%v", r.URL(), err)
	}
	err = resp.JSON(&data)
	return data, err
}

func parseBilibiliUrl(bu string) (vid string, page int, err error) {
	u, err := url.Parse(bu)
	if err != nil {
		return "", 0, err
	}
	if u.Host != "www.bilibili.com" && u.Host != "m.bilibili.com" {
		return "", 0, fmt.Errorf("链接似乎不是bilibili的视频链接")
	}
	re := regexp.MustCompile("/video/(?P<vid>[a-zA-Z0-9]+)")
	parts := re.FindStringSubmatch(u.Path)
	names := re.SubexpNames()
	for _, name := range names {
		if name == "vid" {
			vid = parts[re.SubexpIndex(name)]
		}
	}
	if vid == "" {
		return "", 0, fmt.Errorf("链接似乎不是bilibili的视频链接，未获取到视频id")
	}
	query := u.Query()
	if query.Get("p") != "" {
		pageStr := query.Get("p")
		page, _ = strconv.Atoi(pageStr)
	} else {
		page = 1
	}
	return vid, page, nil
}