package gameserver

import (
	"crypto/sha256"
	_ "embed"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"strings"

	"gac-hkrpg-go/internal/common"
)

// The maintained adapter is embedded separately from scripts/: a disabled
// presentation must not be executed merely because heartbeat lists Lua files.
//
//go:embed gacha_presentation.lua
var gachaPresentationAdapter []byte

// loadGachaPresentationLua supplies the same explicit banner/avatar mapping
// accepted by DoGacha, plus resource-backed art paths. The Client performs its
// own AssetMgr.Exists checks before registering each initialized native clone.
// No user save is read or written here.
func loadGachaPresentationLua() ([]byte, error) {
	verified, policy, err := common.LoadBrowsableGachaBanners()
	if err != nil {
		return nil, err
	}
	if !policy.NativePresentation.Enabled {
		return []byte("\n_G.__GAC_GACHA_PRESENTATION={enabled=false}\n"), nil
	}
	if policy.NativePresentation.Source == "" || policy.NativePresentation.TemplateGachaID == 0 {
		return nil, fmt.Errorf("native gacha presentation template provenance missing")
	}
	var template common.FeaturedGachaBanner
	for _, banner := range verified {
		if banner.ID == policy.NativePresentation.TemplateGachaID {
			template = banner
			break
		}
	}
	if template.ID == 0 || template.AvatarID != 0 {
		return nil, fmt.Errorf("native gacha presentation requires a verified generic template")
	}
	mapped, rules, err := common.LoadLimitedGachaBanners()
	if err != nil {
		return nil, err
	}
	var avatars struct {
		Rows []struct {
			ID   uint32 `json:"AvatarID"`
			Art  string `json:"AvatarCutinFrontImgPath"`
			Icon string `json:"DefaultAvatarHeadIconPath"`
		} `json:"avatar_config"`
	}
	raw, err := common.ReadResourceFile("resources/AvatarConfig.json")
	if err != nil {
		return nil, err
	}
	if err = json.Unmarshal(raw, &avatars); err != nil {
		return nil, err
	}
	byID := make(map[uint32]struct{ art, icon string }, len(avatars.Rows))
	for _, row := range avatars.Rows {
		if _, duplicate := byID[row.ID]; duplicate || row.ID == 0 {
			return nil, fmt.Errorf("duplicate/invalid avatar presentation row %d", row.ID)
		}
		byID[row.ID] = struct{ art, icon string }{row.Art, row.Icon}
	}
	var payload strings.Builder
	fmt.Fprintf(&payload, "\n_G.__GAC_GACHA_PRESENTATION={enabled=true,template_id=%d,template_prefab=%s,rules={five_star_pity=%d,four_star_pity=%d},banners={\n", template.ID, luaNavigationString(template.Prefab), rules.FiveStarPity, rules.FourStarPity)
	for index, banner := range mapped {
		paths, exists := byID[banner.AvatarID]
		if !exists || paths.art == "" || paths.icon == "" {
			return nil, fmt.Errorf("mapped avatar %d has no captured presentation paths", banner.AvatarID)
		}
		fmt.Fprintf(&payload, "{gacha_id=%d,avatar_id=%d,sort_order=%d,art_path=%s,icon_path=%s,four_stars={", banner.GachaID, banner.AvatarID, index+1, luaNavigationString(paths.art), luaNavigationString(paths.icon))
		for _, id := range banner.FourStarIDs {
			four, exists := byID[id]
			if !exists || four.icon == "" {
				return nil, fmt.Errorf("featured four-star %d has no captured portrait", id)
			}
			fmt.Fprintf(&payload, "{avatar_id=%d,portrait_path=%s},", id, luaNavigationString(four.icon))
		}
		payload.WriteString("}},\n")
	}
	payload.WriteString("}}\n")
	// A source update must also replace the owned hooks on a long-lived Client.
	// Otherwise an unchanged mapping keeps the old closure after a new server
	// executable starts. Lua defers the replacement until Warp is closed.
	identity := sha256.New()
	identity.Write([]byte(payload.String()))
	identity.Write(gachaPresentationAdapter)
	fmt.Fprintf(&payload, "_G.__GAC_GACHA_PRESENTATION.digest=%s\n", luaNavigationString(hex.EncodeToString(identity.Sum(nil))))
	// Counters change after draws; do not include them in the static adapter
	// digest or each draw would rebuild every tab and invalidate its selection.
	pity, err := common.ReadLimitedGachaPity()
	if err != nil {
		return nil, err
	}
	fmt.Fprintf(&payload, "_G.__GAC_GACHA_PRESENTATION.pity={since_five_star=%d,since_four_star=%d}\n", pity.SinceFiveStar, pity.SinceFourStar)
	payload.Write(gachaPresentationAdapter)
	return []byte(payload.String()), nil
}