package sdkserver

import (
	"encoding/json"
	"fmt"
	"os"

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

// POST patches fields; PUT explicitly replaces a complete player document.
// Keep raw JSON values so unrelated IDs and numeric values are not rounded.
func preparePlayerDataUpdate(existing, payload []byte, replace bool) ([]byte, error) {
	var patch map[string]json.RawMessage
	if err := json.Unmarshal(payload, &patch); err != nil || patch == nil {
		return nil, fmt.Errorf("player data must be a JSON object")
	}
	result := make(map[string]json.RawMessage)
	if replace {
		for _, key := range []string{"avatars", "lightcones", "relics", "battle_config"} {
			if _, present := patch[key]; !present {
				return nil, fmt.Errorf("full replacement is missing %s; use POST for a partial update", key)
			}
		}
		// FreeSR exports do not necessarily include the inventory editor's
		// material overrides. Omission preserves them; an explicit materials
		// object (including zero counts or {}) still replaces that field.
		if _, present := patch["materials"]; !present && len(existing) != 0 {
			var current map[string]json.RawMessage
			if err := json.Unmarshal(existing, &current); err != nil || current == nil {
				return nil, fmt.Errorf("existing player data is invalid; restore it before applying updates")
			}
			if value, present := current["materials"]; present {
				result["materials"] = value
			}
		}
	} else if err := json.Unmarshal(existing, &result); err != nil || result == nil {
		return nil, fmt.Errorf("existing player data is invalid; restore it before applying updates")
	}
	for key, value := range patch {
		if key == "avatars" && !replace {
			var incoming map[string]json.RawMessage
			if err := json.Unmarshal(value, &incoming); err != nil || len(incoming) == 0 {
				return nil, fmt.Errorf("avatars update must be a non-empty object")
			}
			current := make(map[string]json.RawMessage)
			if raw, found := result[key]; found {
				if err := json.Unmarshal(raw, &current); err != nil || current == nil {
					return nil, fmt.Errorf("existing avatars data is invalid")
				}
			}
			for id, avatar := range incoming {
				current[id] = avatar
			}
			merged, err := json.Marshal(current)
			if err != nil {
				return nil, err
			}
			result[key] = merged
		} else {
			result[key] = value
		}
	}
	out, err := json.MarshalIndent(result, "", "  ")
	if err != nil {
		return nil, err
	}
	var data common.FreesrData
	if err := json.Unmarshal(out, &data); err != nil {
		return nil, fmt.Errorf("invalid player data: %w", err)
	}
	if err := common.ValidateAvatarRoster(data.Avatars); err != nil {
		return nil, err
	}
	if saved, err := common.ReadPersistent(); err == nil {
		if err := common.ValidateAdventureLineup(data.Avatars, saved.Lineups); err != nil {
			return nil, err
		}
	} else if !os.IsNotExist(err) {
		return nil, fmt.Errorf("cannot validate active lineup: %w", err)
	}
	return out, nil
}

func writePlayerDataAtomic(data []byte) error {
	file, err := os.CreateTemp(".", ".gac-freesr-*.tmp")
	if err != nil {
		return err
	}
	name := file.Name()
	defer os.Remove(name)
	if _, err := file.Write(data); err != nil {
		file.Close()
		return err
	}
	if err := file.Sync(); err != nil {
		file.Close()
		return err
	}
	if err := file.Close(); err != nil {
		return err
	}
	return os.Rename(name, "freesr-data.json")
}