import { RedisClientType } from '@redis/client';
import { RedisArgument, RedisFunctions, RedisScripts } from '@redis/client/dist/lib/RESP/types';
import QUERY, { QueryOptions } from './commands/QUERY';

interface GraphMetadata {
  labels: Array<string>;
  relationshipTypes: Array<string>;
  propertyKeys: Array<string>;
}

// https://github.com/RedisGraph/RedisGraph/blob/master/src/resultset/formatters/resultset_formatter.h#L20
enum GraphValueTypes {
  UNKNOWN = 0,
  NULL = 1,
  STRING = 2,
  INTEGER = 3,
  BOOLEAN = 4,
  DOUBLE = 5,
  ARRAY = 6,
  EDGE = 7,
  NODE = 8,
  PATH = 9,
  MAP = 10,
  POINT = 11
}

type GraphEntityRawProperties = Array<[
  id: number,
  ...value: GraphRawValue
]>;

type GraphEdgeRawValue = [
  GraphValueTypes.EDGE,
  [
    id: number,
    relationshipTypeId: number,
    sourceId: number,
    destinationId: number,
    properties: GraphEntityRawProperties
  ]
];

type GraphNodeRawValue = [
  GraphValueTypes.NODE,
  [
    id: number,
    labelIds: Array<number>,
    properties: GraphEntityRawProperties
  ]
];

type GraphPathRawValue = [
  GraphValueTypes.PATH,
  [
    nodes: [
      GraphValueTypes.ARRAY,
      Array<GraphNodeRawValue>
    ],
    edges: [
      GraphValueTypes.ARRAY,
      Array<GraphEdgeRawValue>
    ]
  ]
];

type GraphMapRawValue = [
  GraphValueTypes.MAP,
  Array<string | GraphRawValue>
];

type GraphRawValue = [
  GraphValueTypes.NULL,
  null
] | [
  GraphValueTypes.STRING,
  string
] | [
  GraphValueTypes.INTEGER,
  number
] | [
  GraphValueTypes.BOOLEAN,
  string
] | [
  GraphValueTypes.DOUBLE,
  string
] | [
  GraphValueTypes.ARRAY,
  Array<GraphRawValue>
] | GraphEdgeRawValue | GraphNodeRawValue | GraphPathRawValue | GraphMapRawValue | [
  GraphValueTypes.POINT,
  [
    latitude: string,
    longitude: string
  ]
];

type GraphEntityProperties = Record<string, GraphValue>;

interface GraphEdge {
  id: number;
  relationshipType: string;
  sourceId: number;
  destinationId: number;
  properties: GraphEntityProperties;
}

interface GraphNode {
  id: number;
  labels: Array<string>;
  properties: GraphEntityProperties;
}

interface GraphPath {
  nodes: Array<GraphNode>;
  edges: Array<GraphEdge>;
}

type GraphMap = {
  [key: string]: GraphValue;
};

type GraphValue = null | string | number | boolean | Array<GraphValue> | {
} | GraphEdge | GraphNode | GraphPath | GraphMap | {
  latitude: string;
  longitude: string;
};

export type GraphReply<T> = {
  data?: Array<T>;
};

export type GraphClientType = RedisClientType<{
  graph: {
    query: typeof QUERY,
    roQuery: typeof import('./commands/RO_QUERY.js').default
  }
}, RedisFunctions, RedisScripts>;

export default class Graph {
  #client: GraphClientType;
  #name: string;
  #metadata?: GraphMetadata;

  constructor(
    client: GraphClientType,
    name: string
  ) {
    this.#client = client;
    this.#name = name;
  }

  async query<T>(
    query: RedisArgument,
    options?: QueryOptions
  ) {
    return this.#parseReply<T>(
      await this.#client.graph.query(
        this.#name,
        query,
        options,
        true
      )
    );
  }

  async roQuery<T>(
    query: RedisArgument,
    options?: QueryOptions
  ) {
    return this.#parseReply<T>(
      await this.#client.graph.roQuery(
        this.#name,
        query,
        options,
        true
      )
    );
  }

  #setMetadataPromise?: Promise<GraphMetadata>;

  #updateMetadata(): Promise<GraphMetadata> {
    this.#setMetadataPromise ??= this.#setMetadata()
      .finally(() => this.#setMetadataPromise = undefined);
    return this.#setMetadataPromise;
  }

  // DO NOT use directly, use #updateMetadata instead
  async #setMetadata(): Promise<GraphMetadata> {
    const [labels, relationshipTypes, propertyKeys] = await Promise.all([
      this.#client.graph.roQuery(this.#name, 'CALL db.labels()'),
      this.#client.graph.roQuery(this.#name, 'CALL db.relationshipTypes()'),
      this.#client.graph.roQuery(this.#name, 'CALL db.propertyKeys()')
    ]);

    this.#metadata = {
      labels: this.#cleanMetadataArray(labels.data as Array<[string]>),
      relationshipTypes: this.#cleanMetadataArray(relationshipTypes.data as Array<[string]>),
      propertyKeys: this.#cleanMetadataArray(propertyKeys.data as Array<[string]>)
    };

    return this.#metadata;
  }

  #cleanMetadataArray(arr: Array<[string]>): Array<string> {
    return arr.map(([value]) => value);
  }

  #getMetadata<T extends keyof GraphMetadata>(
    key: T,
    id: number
  ): GraphMetadata[T][number] | Promise<GraphMetadata[T][number]> {
    return this.#metadata?.[key][id] ?? this.#getMetadataAsync(key, id);
  }

  // DO NOT use directly, use #getMetadata instead
  async #getMetadataAsync<T extends keyof GraphMetadata>(
    key: T,
    id: number
  ): Promise<GraphMetadata[T][number]> {
    const value = (await this.#updateMetadata())[key][id];
    if (value === undefined) throw new Error(`Cannot find value from ${key}[${id}]`);
    return value;
  }

  // TODO: reply type
  async #parseReply<T>(reply: any): Promise<GraphReply<T>> {
    if (!reply.data) return reply;

    const promises: Array<Promise<unknown>> = [],
      parsed = {
        metadata: reply.metadata,
        data: reply.data!.map((row: any) => {
          const data: Record<string, GraphValue> = {};
          for (let i = 0; i < row.length; i++) {
            data[reply.headers[i][1]] = this.#parseValue(row[i], promises);
          }

          return data as unknown as T;
        })
      };

    if (promises.length) await Promise.all(promises);

    return parsed;
  }

  #parseValue([valueType, value]: GraphRawValue, promises: Array<Promise<unknown>>): GraphValue {
    switch (valueType) {
      case GraphValueTypes.NULL:
        return null;

      case GraphValueTypes.STRING:
      case GraphValueTypes.INTEGER:
        return value;

      case GraphValueTypes.BOOLEAN:
        return value === 'true';

      case GraphValueTypes.DOUBLE:
        return parseFloat(value);

      case GraphValueTypes.ARRAY:
        return value.map(x => this.#parseValue(x, promises));

      case GraphValueTypes.EDGE:
        return this.#parseEdge(value, promises);

      case GraphValueTypes.NODE:
        return this.#parseNode(value, promises);

      case GraphValueTypes.PATH:
        return {
          nodes: value[0][1].map(([, node]) => this.#parseNode(node, promises)),
          edges: value[1][1].map(([, edge]) => this.#parseEdge(edge, promises))
        };

      case GraphValueTypes.MAP:
        const map: GraphMap = {};
        for (let i = 0; i < value.length; i++) {
          map[value[i++] as string] = this.#parseValue(value[i] as GraphRawValue, promises);
        }

        return map;

      case GraphValueTypes.POINT:
        return {
          latitude: parseFloat(value[0]),
          longitude: parseFloat(value[1])
        };

      default:
        throw new Error(`unknown scalar type: ${valueType}`);
    }
  }

  #parseEdge([
    id,
    relationshipTypeId,
    sourceId,
    destinationId,
    properties
  ]: GraphEdgeRawValue[1], promises: Array<Promise<unknown>>): GraphEdge {
    const edge = {
      id,
      sourceId,
      destinationId,
      properties: this.#parseProperties(properties, promises)
    } as GraphEdge;

    const relationshipType = this.#getMetadata('relationshipTypes', relationshipTypeId);
    if (relationshipType instanceof Promise) {
      promises.push(
        relationshipType.then(value => edge.relationshipType = value)
      );
    } else {
      edge.relationshipType = relationshipType;
    }

    return edge;
  }

  #parseNode([
    id,
    labelIds,
    properties
  ]: GraphNodeRawValue[1], promises: Array<Promise<unknown>>): GraphNode {
    const labels = new Array<string>(labelIds.length);
    for (let i = 0; i < labelIds.length; i++) {
      const value = this.#getMetadata('labels', labelIds[i]);
      if (value instanceof Promise) {
        promises.push(value.then(value => labels[i] = value));
      } else {
        labels[i] = value;
      }
    }

    return {
      id,
      labels,
      properties: this.#parseProperties(properties, promises)
    };
  }

  #parseProperties(raw: GraphEntityRawProperties, promises: Array<Promise<unknown>>): GraphEntityProperties {
    const parsed: GraphEntityProperties = {};
    for (const [id, type, value] of raw) {
      const parsedValue = this.#parseValue([type, value] as GraphRawValue, promises),
        key = this.#getMetadata('propertyKeys', id);
      if (key instanceof Promise) {
        promises.push(key.then(key => parsed[key] = parsedValue));
      } else {
        parsed[key] = parsedValue;
      }
    }

    return parsed;
  }
}