import { PASSWORD_ENTRIES, PASSWORD_ENTRY } from '../../../models/password_entry.ts';
import { USER, USERS } from '../../../models/user.ts';
import { SIGNUP, SIGNUPS } from '../../../models/signups.ts';
import lurid from '@andyburke/lurid';
import { encodeBase64 } from '@std/encoding';
import parse_body from '../../../utils/bodyparser.ts';
import { create_new_session, SESSION_RESULT } from '../auth/index.ts';
import { get_session, get_user, PRECHECK_TABLE, require_user } from '../../../utils/prechecks.ts';
import * as CANNED_RESPONSES from '../../../utils/canned_responses.ts';
import * as bcrypt from '@da/bcrypt';
import { INVITE_CODE, INVITE_CODES } from '../../../models/invites.ts';

// TODO: figure out a better solution for doling out permissions
const DEFAULT_USER_PERMISSIONS: string[] = [
	'files.write.own',
	'invites.create',
	'invites.read.own',
	'self.read',
	'self.write',
	'signups.read.own',
	'topics.read',
	'topics.blurbs.create',
	'topics.blurbs.read',
	'topics.blurbs.write',
	'topics.chat.write',
	'topics.chat.read',
	'topics.essays.create',
	'topics.essays.read',
	'topics.essays.write',
	'topics.posts.create',
	'topics.posts.write',
	'topics.posts.read',
	'users.read',
	'watches.create.own',
	'watches.read.own',
	'watches.write.own'
];

export const PRECHECKS: PRECHECK_TABLE = {};

// GET /api/users - get users
// query parameters:
//   partial_id: the partial id subset you would like to match (remember, lurids are lexigraphically sorted)
PRECHECKS.GET = [get_session, get_user, require_user, (_req: Request, meta: Record<string, any>): Response | undefined => {
	const can_read_others = meta.user?.permissions?.includes('users.read');

	if (!can_read_others) {
		return CANNED_RESPONSES.permission_denied();
	}
}];
export async function GET(_req: Request, meta: Record<string, any>): Promise<Response> {
	const query: URLSearchParams = meta.query;
	const partial_id: string | undefined = query.get('partial_id')?.toLowerCase().trim();

	const has_partial_id = typeof partial_id === 'string' && partial_id.length >= 2;
	if (!has_partial_id) {
		return Response.json({
			error: {
				message: 'You must specify a `partial_id` query parameter.',
				cause: 'missing_query_parameter'
			}
		}, {
			status: 400
		});
	}

	const limit = Math.min(parseInt(query.get('limit') ?? '10'), 100);
	const users = await USERS.find({
		id: partial_id
	}, {
		limit
	});

	return Response.json(users, {
		status: 200
	});
}

// POST /api/users - Create user
export async function POST(req: Request, meta: Record<string, any>): Promise<Response> {
	try {
		const new_user_id = lurid();
		const now = new Date().toISOString();

		const body = await parse_body(req);
		const username: string = body.username?.trim() ?? '';
		const normalized_username = username.toLowerCase();
		const submitted_invite_code = body.invite_code?.trim();

		const existing_user_with_username = (await USERS.find({
			normalized_username
		})).shift();
		if (existing_user_with_username) {
			return Response.json({
				error: {
					cause: 'username_conflict',
					message: 'Username is already in use.'
				}
			}, {
				status: 400
			});
		}

		const password_hash: string = body.password_hash ?? (typeof body.password === 'string'
			? encodeBase64(
				await crypto.subtle.digest('SHA-256', new TextEncoder().encode(body.password))
			)
			: '');
		if (password_hash.length < 32) {
			return Response.json({
				error: {
					cause: 'invalid password hash',
					message: 'Password must be hashed with a stronger algorithm.'
				}
			}, {
				status: 400
			});
		}

		const at_least_one_existing_user = (await USERS.all({
			limit: 1,
			offset: 0
		})).shift()?.load();

		let root_invite_code_secret = undefined;
		if (!at_least_one_existing_user) {
			root_invite_code_secret = lurid();

			const root_invite_code: INVITE_CODE = {
				id: lurid(),
				code: root_invite_code_secret,
				creator_id: new_user_id,
				timestamps: {
					created: now,
					expires: new Date(new Date(now).valueOf() + 1_000).toISOString()
				}
			};

			await INVITE_CODES.create(root_invite_code);
		}

		const secret_code = submitted_invite_code ?? root_invite_code_secret;
		if (typeof secret_code !== 'string' || secret_code.length < 3) {
			return Response.json({
				error: {
					cause: 'missing_invite_code',
					message: 'You need to specify an invite code.'
				}
			}, {
				status: 400
			});
		}

		const invite_code: INVITE_CODE | undefined = (await INVITE_CODES.find({
			code: secret_code
		})).shift()?.load();

		const is_expired = now >= (invite_code?.timestamps.expires ?? '0000-01-01T00:00:00.000Z');
		const is_used = (await SIGNUPS.find({
			referring_invite_code_id: invite_code?.id
		}, {
			limit: 1
		})).length > 0;
		const is_cancelled = !!invite_code?.timestamps?.cancelled;

		if (!invite_code || is_expired || is_used || is_cancelled) {
			return Response.json({
				error: {
					cause: 'invalid_signup_code',
					message: 'Could not find an active signup code given this information.',
					meta: {
						exists: !!invite_code,
						is_expired,
						is_used,
						is_cancelled
					}
				}
			}, {
				status: 400
			});
		}

		const signup: SIGNUP = {
			id: lurid(),
			user_id: new_user_id,
			invite_code_id: invite_code?.id ?? 'able-able-able-able-able-able-able-able-able-able',
			referring_user_id: invite_code?.creator_id ?? new_user_id,
			timestamps: {
				created: now
			}
		};
		await SIGNUPS.create(signup);

		const user: USER = {
			id: new_user_id,
			username,
			permissions: DEFAULT_USER_PERMISSIONS,
			timestamps: {
				created: now,
				updated: now
			}
		};

		await USERS.create(user);

		// automatically salted
		const hashed_password_value = bcrypt.hashSync(password_hash);

		const password_entry: PASSWORD_ENTRY = {
			user_id: user.id,
			hash: hashed_password_value,
			timestamps: {
				created: now,
				updated: now
			}
		};

		await PASSWORD_ENTRIES.create(password_entry);

		const session_result: SESSION_RESULT = await create_new_session({
			user,
			expires: undefined
		});

		// TODO: verify this redirect is ok?
		const headers = session_result.headers;
		let status = 201;
		if (typeof meta?.query?.redirect === 'string') {
			const url = new URL(req.url);
			headers.append('location', `${url.origin}${meta.query.redirect}`);
			status = 302;
		}

		return Response.json({
			user,
			session: session_result.session
		}, {
			status,
			headers
		});
	} catch (error) {
		return Response.json({
			error: {
				message: (error as Error).message ?? 'Unknown Error!',
				cause: (error as Error).cause ?? 'unknown'
			}
		}, { status: 500 });
	}
}