package store

import (
	"context"
	"encoding/json"
	"strings"

	"github.com/easyai/easyai-ai-gateway/apps/api/internal/auth"
	"github.com/jackc/pgx/v5"
)

type ConversationMessageInput struct {
	Hash         string
	Role         string
	Snapshot     map[string]any
	AssetSHA256s []string
}

type TaskMessageRefInput struct {
	MessageID string
	Position  int
}

type ConversationMessageRef struct {
	MessageID string         `json:"messageId"`
	Position  int            `json:"position"`
	Message   map[string]any `json:"message"`
}

func (s *Store) EnsureConversation(ctx context.Context, user *auth.User, conversationKey string, metadata map[string]any) (string, error) {
	conversationKey = strings.TrimSpace(conversationKey)
	if conversationKey == "" {
		return "", nil
	}
	userID := ""
	gatewayUserID := ""
	if user != nil {
		userID = strings.TrimSpace(user.ID)
		gatewayUserID = strings.TrimSpace(user.GatewayUserID)
	}
	if userID == "" {
		userID = "anonymous"
	}
	metadataJSON, _ := json.Marshal(emptyObjectIfNil(metadata))
	var conversationID string
	err := s.pool.QueryRow(ctx, `
INSERT INTO gateway_conversations (user_id, gateway_user_id, conversation_key, metadata)
VALUES ($1, NULLIF($2, '')::uuid, $3, $4::jsonb)
ON CONFLICT (user_id, conversation_key) DO UPDATE
SET gateway_user_id = COALESCE(gateway_conversations.gateway_user_id, EXCLUDED.gateway_user_id),
    metadata = gateway_conversations.metadata || EXCLUDED.metadata,
    updated_at = now()
RETURNING id::text`, userID, gatewayUserID, conversationKey, string(metadataJSON)).Scan(&conversationID)
	return conversationID, err
}

func (s *Store) UpsertConversationMessages(ctx context.Context, conversationID string, messages []ConversationMessageInput) ([]TaskMessageRefInput, int, error) {
	if strings.TrimSpace(conversationID) == "" || len(messages) == 0 {
		return nil, 0, nil
	}
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, 0, err
	}
	defer tx.Rollback(ctx)

	refs := make([]TaskMessageRefInput, 0, len(messages))
	newCount := 0
	for index, message := range messages {
		snapshotJSON, _ := json.Marshal(emptyObjectIfNil(message.Snapshot))
		var messageID string
		var inserted bool
		if err := tx.QueryRow(ctx, `
INSERT INTO gateway_conversation_messages (
  conversation_id, message_hash, role, message_snapshot, asset_sha256s
)
VALUES ($1::uuid, $2, NULLIF($3, ''), $4::jsonb, $5)
ON CONFLICT (conversation_id, message_hash) DO UPDATE
SET updated_at = gateway_conversation_messages.updated_at
RETURNING id::text, (xmax = 0) AS inserted`,
			conversationID,
			message.Hash,
			message.Role,
			string(snapshotJSON),
			message.AssetSHA256s,
		).Scan(&messageID, &inserted); err != nil {
			return nil, 0, err
		}
		if inserted {
			newCount++
		}
		refs = append(refs, TaskMessageRefInput{MessageID: messageID, Position: index})
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, 0, err
	}
	return refs, newCount, nil
}

func (s *Store) ListTaskConversationMessages(ctx context.Context, taskID string) ([]ConversationMessageRef, error) {
	rows, err := s.pool.Query(ctx, `
SELECT refs.message_id::text, refs.position, messages.message_snapshot
FROM gateway_task_message_refs refs
JOIN gateway_conversation_messages messages ON messages.id = refs.message_id
WHERE refs.task_id = $1::uuid
ORDER BY refs.position ASC`, taskID)
	if err != nil {
		if IsUndefinedDatabaseObject(err) {
			return nil, nil
		}
		return nil, err
	}
	defer rows.Close()

	items := make([]ConversationMessageRef, 0)
	for rows.Next() {
		var item ConversationMessageRef
		var snapshot []byte
		if err := rows.Scan(&item.MessageID, &item.Position, &snapshot); err != nil {
			return nil, err
		}
		item.Message = decodeObject(snapshot)
		items = append(items, item)
	}
	return items, rows.Err()
}

func insertTaskMessageRefs(ctx context.Context, tx pgx.Tx, taskID string, refs []TaskMessageRefInput) error {
	if len(refs) == 0 {
		return nil
	}
	for _, ref := range refs {
		if strings.TrimSpace(ref.MessageID) == "" {
			continue
		}
		if _, err := tx.Exec(ctx, `
INSERT INTO gateway_task_message_refs (task_id, message_id, position)
VALUES ($1::uuid, $2::uuid, $3)
ON CONFLICT (task_id, position) DO UPDATE
SET message_id = EXCLUDED.message_id`,
			taskID,
			ref.MessageID,
			ref.Position,
		); err != nil {
			return err
		}
	}
	return nil
}