import { generateId } from 'better-auth';
import { getAuthTables } from 'better-auth/db';
import type { Adapter, BetterAuthOptions, Where } from 'better-auth/types';
import { jsonify, RecordId, Surreal } from 'surrealdb';
import { withApplyDefault } from './utils';

const createTransform = (options: BetterAuthOptions) => {
    const schema = getAuthTables(options);

    function transformSelect(select: string[], model: string): string[] {
        if (!select || select.length === 0) return [];
        return select.map(field => getField(model, field));
    }

    function getField(model: string, field: string) {
        if (field === "id") {
            return field;
        }
        const f = schema[model].fields[field];
        return f.fieldName || field;
    }

    return {
        transformInput(data: Record<string, any>, model: string, action: "update" | "create") {
            const transformedData: Record<string, any> =
                action === "update"
                    ? {}
                    : {
                        id: options.advanced?.generateId
                            ? options.advanced.generateId({ model })
                            : data.id || generateId(),
                    };

            const fields = schema[model].fields;
            for (const field in fields) {
                const value = data[field];
                if (value === undefined && !fields[field].defaultValue) {
                    continue;
                }
                transformedData[fields[field].fieldName || field] = withApplyDefault(value, fields[field], action);
            }
            return transformedData;
        },
        transformOutput(data: Record<string, any>, model: string, select: string[] = []) {
            if (!data) return null;
            const transformedData: Record<string, any> =
                data.id || data._id
                    ? select.length === 0 || select.includes("id")
                        ? { id: data.id }
                        : {}
                    : {};
            const tableSchema = schema[model].fields;
            for (const key in tableSchema) {
                if (select.length && !select.includes(key)) {
                    continue;
                }
                const field = tableSchema[key];
                if (field) {
                    transformedData[key] = data[field.fieldName || key];
                }
            }
            return transformedData as any;
        },
        convertWhereClause(where: Where[], model: string) {
            return where.map(clause => {
                const { field: _field, value, operator } = clause;
                const field = getField(model, _field);
                switch (operator) {
                    case "eq":
                        return (field === 'id' || value instanceof RecordId) ?
                            `${field} = ${jsonify(value)}`
                            :
                            `${field} = '${jsonify(value)}'`
                    case "in":
                        return `${field} IN [${jsonify(value)}]`;
                    case "contains":
                        return `${field} CONTAINS '${jsonify(value)}'`;
                    case "starts_with":
                        return `string::starts_with(${field},'${value}')`;
                    case "ends_with":
                        return `string::ends_with(${field},'${value}')`;
                    default:
                        return (field === 'id' || value instanceof RecordId) ?
                            `${field} = ${jsonify(value)}`
                            :
                            `${field} = '${jsonify(value)}'`
                }
            }).join(' AND ');
        },
        transformSelect,
        getField,
    };
};

export const surrealAdapter = (db: Surreal) => (options: BetterAuthOptions) => {
    if (!db) {
        throw new Error("SurrealDB adapter requires a SurrealDB client");
    }
    const { transformInput, transformOutput, convertWhereClause, getField } = createTransform(options);

    return {
        id: "surreal",
        create: async ({ model, data }) => {
            const transformed = transformInput(data, model, "create");
            const [result] = await db.create(model, transformed);
            return transformOutput(result, model);
        },
        findOne: async ({ model, where, select = [] }) => {
            const whereClause = convertWhereClause(where, model);
            const selectClause = select.length > 0 && select.map((f) => getField(model, f)) || []
            const query = select.length > 0 ? `SELECT ${selectClause.join(', ')} FROM ${model} WHERE ${whereClause} LIMIT 1` : `SELECT * FROM ${model} WHERE ${whereClause} LIMIT 1`;
            const result = await db.query<[any[]]>(query)
            return transformOutput(result[0][0], model, select);
        },
        findMany: async ({ model, where, sortBy, limit, offset }) => {
            let query = `SELECT * FROM ${model}`;
            if (where) {
                const whereClause = convertWhereClause(where, model);
                query += ` WHERE ${whereClause}`;
            }
            if (sortBy) {
                query += ` ORDER BY ${getField(model, sortBy.field)} ${sortBy.direction}`;
            }
            if (limit !== undefined) {
                query += ` LIMIT ${limit}`;
            }
            if (offset !== undefined) {
                query += ` START ${offset}`;
            }
            const [results] = await db.query<[any[]]>(query);
            return results.map(record => transformOutput(record, model));
        },
        count: async ({ model, where }) => {
            const whereClause = where ? convertWhereClause(where, model) : '';
            const query = `SELECT count(${whereClause}) FROM ${model} GROUP ALL`;
            const [result] = await db.query<[any[]]>(query);
            const res = result[0];
            return res.count;
        },
        update: async ({ model, where, update }) => {
            const whereClause = convertWhereClause(where, model);
            const transformedUpdate = transformInput(update, model, "update");
            const [result] = await db.query<[any[]]>(`UPDATE ${model} MERGE ${JSON.stringify(transformedUpdate)} WHERE ${whereClause}`);
            return transformOutput(result[0], model);
        },
        delete: async ({ model, where }) => {
            const whereClause = convertWhereClause(where, model);
            await db.query(`DELETE FROM ${model} WHERE ${whereClause}`);
        },
        deleteMany: async ({ model, where }) => {
            const whereClause = convertWhereClause(where, model);
            const [result] = await db.query<[any[]]>(`DELETE FROM ${model} WHERE ${whereClause}`);
            return result.length;
        },
        updateMany: async ({ model, where, update }) => {
            const whereClause = convertWhereClause(where, model);
            const transformedUpdate = transformInput(update, model, "update");
            const [result] = await db.query<[any[]]>(`UPDATE ${model} MERGE ${JSON.stringify(transformedUpdate)} WHERE ${whereClause}`);
            return transformOutput(result[0], model);
        },
    } satisfies Adapter;
};