/**
 * Platform (SaaS) backend — communicates with api.mem0.ai.
 */

import type { PlatformConfig } from "../config.js";
import { isAgentMode } from "../state.js";
import { CLI_VERSION } from "../version.js";
import {
	APIError,
	type AddOptions,
	AuthError,
	type Backend,
	type DeleteOptions,
	type EntityIds,
	type ListOptions,
	NotFoundError,
	type SearchOptions,
} from "./base.js";

export class PlatformBackend implements Backend {
	private baseUrl: string;
	private headers: Record<string, string>;

	constructor(config: PlatformConfig) {
		this.baseUrl = config.baseUrl.replace(/\/+$/, "");
		this.headers = {
			Authorization: `Token ${config.apiKey}`,
			"Content-Type": "application/json",
			"X-Mem0-Source": "cli",
			"X-Mem0-Client-Language": "node",
			"X-Mem0-Client-Version": CLI_VERSION,
		};
	}

	private async _request(
		method: string,
		path: string,
		opts?: { json?: unknown; params?: Record<string, string> },
	): Promise<unknown> {
		let url = `${this.baseUrl}${path}`;
		if (opts?.params) {
			const qs = new URLSearchParams(opts.params).toString();
			url += `?${qs}`;
		}

		const headers = {
			...this.headers,
			"X-Mem0-Caller-Type": isAgentMode() ? "agent" : "user",
		};

		const fetchOpts: RequestInit = {
			method,
			headers,
			signal: AbortSignal.timeout(30_000),
		};
		if (opts?.json) {
			fetchOpts.body = JSON.stringify(opts.json);
		}

		const resp = await fetch(url, fetchOpts);

		if (resp.status === 401) {
			throw new AuthError();
		}
		if (resp.status === 404) {
			throw new NotFoundError(path);
		}
		if (resp.status === 400) {
			let detail: string;
			try {
				const body = (await resp.json()) as Record<string, unknown>;
				detail =
					((body.detail ?? body.message ?? JSON.stringify(body)) as string) ??
					resp.statusText;
			} catch {
				detail = resp.statusText;
			}
			throw new APIError(path, detail);
		}
		if (!resp.ok) {
			let detail: string = resp.statusText;
			try {
				const body = (await resp.json()) as Record<string, unknown>;
				detail = (body.detail ?? body.message ?? resp.statusText) as string;
			} catch {
				/* ignore */
			}
			throw new Error(`HTTP ${resp.status}: ${detail}`);
		}
		if (resp.status === 204) {
			return {};
		}
		return resp.json();
	}

	async add(
		content?: string,
		messages?: Record<string, unknown>[],
		opts: AddOptions = {},
	): Promise<Record<string, unknown>> {
		const payload: Record<string, unknown> = {};

		if (messages) {
			payload.messages = messages;
		} else if (content) {
			payload.messages = [{ role: "user", content }];
		}

		if (opts.userId) payload.user_id = opts.userId;
		if (opts.agentId) payload.agent_id = opts.agentId;
		if (opts.appId) payload.app_id = opts.appId;
		if (opts.runId) payload.run_id = opts.runId;
		if (opts.metadata) payload.metadata = opts.metadata;
		if (opts.immutable) payload.immutable = true;
		if (opts.infer === false) payload.infer = false;
		if (opts.expires) payload.expiration_date = opts.expires;
		if (opts.categories) payload.categories = opts.categories;
		if (opts.enableGraph) payload.enable_graph = true;

		return (await this._request("POST", "/v1/memories/", {
			json: payload,
		})) as Record<string, unknown>;
	}

	private _buildFilters(opts: {
		userId?: string;
		agentId?: string;
		appId?: string;
		runId?: string;
		extraFilters?: Record<string, unknown>;
	}): Record<string, unknown> | undefined {
		// If caller passed a pre-built filter structure, use it directly
		if (
			opts.extraFilters &&
			("AND" in opts.extraFilters || "OR" in opts.extraFilters)
		) {
			return opts.extraFilters;
		}

		const andConditions: Record<string, unknown>[] = [];
		if (opts.userId) andConditions.push({ user_id: opts.userId });
		if (opts.agentId) andConditions.push({ agent_id: opts.agentId });
		if (opts.appId) andConditions.push({ app_id: opts.appId });
		if (opts.runId) andConditions.push({ run_id: opts.runId });

		if (opts.extraFilters) {
			for (const [k, v] of Object.entries(opts.extraFilters)) {
				andConditions.push({ [k]: v });
			}
		}

		if (andConditions.length === 1) return andConditions[0];
		if (andConditions.length > 1) return { AND: andConditions };
		return undefined;
	}

	async search(
		query: string,
		opts: SearchOptions = {},
	): Promise<Record<string, unknown>[]> {
		const payload: Record<string, unknown> = {
			query,
			top_k: opts.topK ?? 10,
			threshold: opts.threshold ?? 0.3,
		};

		const apiFilters = this._buildFilters({
			userId: opts.userId,
			agentId: opts.agentId,
			appId: opts.appId,
			runId: opts.runId,
			extraFilters: opts.filters,
		});
		if (apiFilters) payload.filters = apiFilters;
		if (opts.rerank) payload.rerank = true;
		if (opts.keyword) payload.keyword_search = true;
		if (opts.fields) payload.fields = opts.fields;
		if (opts.enableGraph) payload.enable_graph = true;

		const result = (await this._request("POST", "/v2/memories/search/", {
			json: payload,
		})) as unknown;
		if (Array.isArray(result)) return result;
		const obj = result as Record<string, unknown>;
		return (obj.results ?? obj.memories ?? []) as Record<string, unknown>[];
	}

	async get(memoryId: string): Promise<Record<string, unknown>> {
		return (await this._request("GET", `/v1/memories/${memoryId}/`)) as Record<
			string,
			unknown
		>;
	}

	async listMemories(
		opts: ListOptions = {},
	): Promise<Record<string, unknown>[]> {
		const payload: Record<string, unknown> = {};
		const params: Record<string, string> = {
			page: String(opts.page ?? 1),
			page_size: String(opts.pageSize ?? 100),
		};

		const extra: Record<string, unknown> = {};
		if (opts.category) {
			extra.categories = { contains: opts.category };
		}
		if (opts.after) {
			extra.created_at = {
				...(extra.created_at as Record<string, unknown> | undefined),
				gte: opts.after,
			};
		}
		if (opts.before) {
			extra.created_at = {
				...(extra.created_at as Record<string, unknown> | undefined),
				lte: opts.before,
			};
		}

		const apiFilters = this._buildFilters({
			userId: opts.userId,
			agentId: opts.agentId,
			appId: opts.appId,
			runId: opts.runId,
			extraFilters: Object.keys(extra).length > 0 ? extra : undefined,
		});
		if (apiFilters) payload.filters = apiFilters;
		if (opts.enableGraph) payload.enable_graph = true;

		const result = (await this._request("POST", "/v2/memories/", {
			json: payload,
			params,
		})) as unknown;
		if (Array.isArray(result)) return result;
		const obj = result as Record<string, unknown>;
		return (obj.results ?? obj.memories ?? []) as Record<string, unknown>[];
	}

	async update(
		memoryId: string,
		content?: string,
		metadata?: Record<string, unknown>,
	): Promise<Record<string, unknown>> {
		const payload: Record<string, unknown> = {};
		if (content) payload.text = content;
		if (metadata) payload.metadata = metadata;
		return (await this._request("PUT", `/v1/memories/${memoryId}/`, {
			json: payload,
		})) as Record<string, unknown>;
	}

	async delete(
		memoryId?: string,
		opts: DeleteOptions = {},
	): Promise<Record<string, unknown>> {
		if (opts.all) {
			const params: Record<string, string> = {};
			if (opts.userId) params.user_id = opts.userId;
			if (opts.agentId) params.agent_id = opts.agentId;
			if (opts.appId) params.app_id = opts.appId;
			if (opts.runId) params.run_id = opts.runId;
			return (await this._request("DELETE", "/v1/memories/", {
				params,
			})) as Record<string, unknown>;
		}
		if (memoryId) {
			return (await this._request(
				"DELETE",
				`/v1/memories/${memoryId}/`,
			)) as Record<string, unknown>;
		}
		throw new Error("Either memoryId or --all is required");
	}

	async deleteEntities(opts: EntityIds): Promise<Record<string, unknown>> {
		// v2 endpoint: DELETE /v2/entities/{entity_type}/{entity_id}/
		const typeMap: [string, string | undefined][] = [
			["user", opts.userId],
			["agent", opts.agentId],
			["app", opts.appId],
			["run", opts.runId],
		];
		const entities = typeMap.filter(([, v]) => v) as [string, string][];
		if (entities.length === 0) {
			throw new Error("At least one entity ID is required for deleteEntities.");
		}
		// Delete each provided entity via the v2 path-based endpoint
		let result: Record<string, unknown> = {};
		for (const [entityType, entityId] of entities) {
			result = (await this._request(
				"DELETE",
				`/v2/entities/${entityType}/${entityId}/`,
			)) as Record<string, unknown>;
		}
		return result;
	}

	async ping(): Promise<Record<string, unknown>> {
		return (await this._request("GET", "/v1/ping/")) as Record<string, unknown>;
	}

	async status(
		opts: { userId?: string; agentId?: string } = {},
	): Promise<Record<string, unknown>> {
		try {
			await this.ping();
			return { connected: true, backend: "platform", base_url: this.baseUrl };
		} catch (e) {
			return {
				connected: false,
				backend: "platform",
				error: e instanceof Error ? e.message : String(e),
			};
		}
	}

	async entities(entityType: string): Promise<Record<string, unknown>[]> {
		const result = (await this._request("GET", "/v1/entities/")) as unknown;
		let items: Record<string, unknown>[];
		if (Array.isArray(result)) {
			items = result;
		} else {
			items = ((result as Record<string, unknown>).results ?? []) as Record<
				string,
				unknown
			>[];
		}

		const typeMap: Record<string, string> = {
			users: "user",
			agents: "agent",
			apps: "app",
			runs: "run",
		};
		const targetType = typeMap[entityType];
		if (targetType) {
			items = items.filter(
				(e) => (e.type as string | undefined)?.toLowerCase() === targetType,
			);
		}
		return items;
	}

	async listEvents(): Promise<Record<string, unknown>[]> {
		const result = (await this._request("GET", "/v1/events/")) as unknown;
		if (Array.isArray(result)) return result;
		return ((result as Record<string, unknown>).results ?? []) as Record<
			string,
			unknown
		>[];
	}

	async getEvent(eventId: string): Promise<Record<string, unknown>> {
		return (await this._request("GET", `/v1/event/${eventId}/`)) as Record<
			string,
			unknown
		>;
	}
}