// Package cards fixes what IMVU's servers no longer send the client's avatar cards: the AP+ badge. The card shows it
// when avatarcard.php's answer has show_ap_plus, which IMVU stopped sending; whether someone has AP+ is public on
// their IMVU profile (api.imvu.com/user/user-<id>, is_ap_plus), as the friends list and Find People still show.
package cards

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"

	"git.t5de.dev/t5de/t5de-proxy/internal/proxy"
)

// keep is how long an account's AP+ is remembered.
const keep = 10 * time.Minute

// Cards adds show_ap_plus to avatar cards of people with AP+.
type Cards struct {
	// Client fetches IMVU's public profiles (nil: http.DefaultClient).
	Client *http.Client
	// Base is IMVU's API ("" for https://api.imvu.com).
	Base string

	mu    sync.Mutex
	known map[int64]apPlus
}

type apPlus struct {
	has bool
	at  time.Time
}

func (c *Cards) Intercept(x *proxy.Exchange) error {
	if !strings.EqualFold(x.URL.Hostname(), "client-dynamic.imvu.com") || x.URL.Path != "/api/avatarcard.php" {
		return nil
	}
	cid, err := strconv.ParseInt(x.URL.Query().Get("cid"), 10, 64)
	if err != nil || cid <= 0 {
		return nil
	}
	x.ModifyResponse = func(resp *http.Response, body []byte) ([]byte, error) {
		var card map[string]json.RawMessage
		if resp.StatusCode != http.StatusOK || json.Unmarshal(body, &card) != nil || set(card["show_ap_plus"]) {
			return body, nil
		}
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		if !c.has(ctx, cid) {
			return body, nil
		}
		card["show_ap_plus"] = json.RawMessage("1")
		return json.Marshal(card)
	}
	return nil
}

// set reports whether a JSON value counts as set in the card's JavaScript (truthy).
func set(v json.RawMessage) bool {
	s := strings.TrimSpace(string(v))
	return s != "" && s != "null" && s != "false" && s != "0" && s != `""` && s != `"0"`
}

// has reports whether an account has AP+ (false if IMVU can't say).
func (c *Cards) has(ctx context.Context, id int64) bool {
	c.mu.Lock()
	k, ok := c.known[id]
	c.mu.Unlock()
	if ok && time.Since(k.at) < keep {
		return k.has
	}
	base := c.Base
	if base == "" {
		base = "https://api.imvu.com"
	}
	u := fmt.Sprintf("%s/user/user-%d", base, id)
	req, err := http.NewRequestWithContext(ctx, "GET", u, nil)
	if err != nil {
		return false
	}
	client := c.Client
	if client == nil {
		client = http.DefaultClient
	}
	resp, err := client.Do(req)
	if err != nil {
		return k.has
	}
	defer resp.Body.Close()
	var profile struct {
		Denormalized map[string]struct {
			Data struct {
				IsAPPlus bool `json:"is_ap_plus"`
			} `json:"data"`
		} `json:"denormalized"`
	}
	if resp.StatusCode != http.StatusOK || json.NewDecoder(resp.Body).Decode(&profile) != nil {
		return k.has
	}
	has := profile.Denormalized[fmt.Sprintf("https://api.imvu.com/user/user-%d", id)].Data.IsAPPlus
	c.mu.Lock()
	if c.known == nil {
		c.known = map[int64]apPlus{}
	}
	c.known[id] = apPlus{has: has, at: time.Now()}
	c.mu.Unlock()
	return has
}