// API client for Wotra backend.
// Base URL: /api (relative, works both in dev proxy and production)
//
// Offline fallback: if a mutation throws a network error (TypeError: Failed to fetch),
// the call enqueues the operation in the Dexie outbox and resolves with the local object.
// The background sync loop will push the outbox to the server when connectivity returns.

import { db } from '$lib/stores/db';

const API_BASE = '/api';

function getToken(): string {
	return localStorage.getItem('auth_token') ?? '';
}

export function setToken(token: string) {
	localStorage.setItem('auth_token', token);
}

export function hasToken(): boolean {
	return !!localStorage.getItem('auth_token');
}

function isNetworkError(e: unknown): boolean {
	return e instanceof TypeError && e.message.toLowerCase().includes('fetch');
}

async function request<T>(method: string, path: string, body?: unknown): Promise<T> {
	const res = await fetch(`${API_BASE}${path}`, {
		method,
		headers: {
			'Content-Type': 'application/json',
			Authorization: `Bearer ${getToken()}`
		},
		body: body !== undefined ? JSON.stringify(body) : undefined
	});
	if (!res.ok) {
		const err = await res.json().catch(() => ({ error: res.statusText }));
		throw new ApiError(res.status, err.error ?? res.statusText);
	}
	if (res.status === 204) return undefined as T;
	return res.json();
}

/** Enqueue an outbox item for offline push. */
async function enqueue(entity: string, entity_id: string, op: 'upsert' | 'delete', payload: unknown) {
	await db.outbox.add({
		entity,
		entity_id,
		op,
		payload: JSON.stringify(payload),
		created_at: Date.now()
	});
}

export class ApiError extends Error {
	constructor(
		public status: number,
		message: string
	) {
		super(message);
	}
}

// ─── Types ──────────────────────────────────────────────────────────────────

export interface Entry {
	id: string;
	start_time: number; // unix ms UTC
	end_time: number | null;
	auto_stopped: boolean;
	note: string;
	day_key: string;
	updated_at: number;
}

export interface ClosedDay {
	day_key: string;
	start_time: number | null;
	end_time: number | null;
	worked_ms: number;
	kind: 'work' | 'holiday' | 'vacation' | 'sick';
	closed_at: number;
	updated_at: number;
}

export interface ClosedWeek {
	week_key: string;
	expected_ms: number;
	worked_ms: number;
	delta_ms: number;
	closed_at: number;
	updated_at: number;
}

export interface Settings {
	id: string; // UUID
	effective_from: string;
	hours_per_week: number;
	workdays_mask: number;
	timezone: string;
	created_at: number;
	updated_at: number;
}

export interface BalanceAdjustment {
	id: string;
	delta_ms: number;
	note: string;
	effective_at: number; // unix ms
	created_at: number;
	updated_at: number;
}

export interface BalanceSummary {
	total_delta_ms: number;
	weeks_delta_ms: number;
	adjustments_delta_ms: number;
	closed_week_count: number;
	adjustment_count: number;
}

// ─── Entries ─────────────────────────────────────────────────────────────────

export const entries = {
	start: async (note = ''): Promise<Entry> => {
		try {
			return await request<Entry>('POST', '/entries/start', { note });
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const entry: Entry = {
				id: crypto.randomUUID(),
				start_time: Date.now(),
				end_time: null,
				auto_stopped: false,
				note,
				day_key: new Date().toISOString().slice(0, 10),
				updated_at: Date.now()
			};
			await db.entries.put(entry);
			await enqueue('entries', entry.id, 'upsert', entry);
			return entry;
		}
	},

	createInterval: async (startTime: number, endTime: number, note = ''): Promise<Entry> => {
		try {
			return await request<Entry>('POST', '/entries', { start_time: startTime, end_time: endTime, note });
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const entry: Entry = {
				id: crypto.randomUUID(),
				start_time: startTime,
				end_time: endTime,
				auto_stopped: false,
				note,
				day_key: new Date(startTime).toISOString().slice(0, 10),
				updated_at: Date.now()
			};
			await db.entries.put(entry);
			await enqueue('entries', entry.id, 'upsert', entry);
			return entry;
		}
	},

	stop: async (id: string): Promise<Entry> => {
		try {
			return await request<Entry>('POST', `/entries/${id}/stop`);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const existing = await db.entries.get(id);
			if (!existing) throw e;
			const updated: Entry = { ...existing, end_time: Date.now(), updated_at: Date.now() };
			await db.entries.put(updated);
			await enqueue('entries', id, 'upsert', updated);
			return updated;
		}
	},

	list: (from?: string, to?: string) => {
		const params = new URLSearchParams();
		if (from) params.set('from', from);
		if (to) params.set('to', to);
		return request<Entry[]>('GET', `/entries?${params}`);
	},

	update: async (id: string, body: { start_time?: number; end_time?: number; note?: string }): Promise<Entry> => {
		try {
			return await request<Entry>('PUT', `/entries/${id}`, body);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const existing = await db.entries.get(id);
			if (!existing) throw e;
			const updated: Entry = { ...existing, ...body, updated_at: Date.now() };
			await db.entries.put(updated);
			await enqueue('entries', id, 'upsert', updated);
			return updated;
		}
	},

	delete: async (id: string): Promise<void> => {
		try {
			return await request<void>('DELETE', `/entries/${id}`);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			await db.entries.delete(id);
			await enqueue('entries', id, 'delete', { id, updated_at: Date.now() });
		}
	}
};

// ─── Days ────────────────────────────────────────────────────────────────────

export const days = {
	list: (from?: string, to?: string) => {
		const params = new URLSearchParams();
		if (from) params.set('from', from);
		if (to) params.set('to', to);
		return request<ClosedDay[]>('GET', `/days?${params}`);
	},
	close: (dayKey: string) => request<ClosedDay>('POST', `/days/${dayKey}/close`),
	mark: (dayKey: string, kind: 'holiday' | 'vacation' | 'sick') =>
		request<ClosedDay>('POST', `/days/${dayKey}/mark`, { kind }),
	reopen: (dayKey: string) => request<void>('DELETE', `/days/${dayKey}/close`)
};

// ─── Weeks ───────────────────────────────────────────────────────────────────

export const weeks = {
	list: (from?: string, to?: string) => {
		const params = new URLSearchParams();
		if (from) params.set('from', from);
		if (to) params.set('to', to);
		return request<ClosedWeek[]>('GET', `/weeks?${params}`);
	},
	close: (weekKey: string) => request<ClosedWeek>('POST', `/weeks/${weekKey}/close`),
	reopen: (weekKey: string) => request<void>('DELETE', `/weeks/${weekKey}/close`),
	balance: () => request<BalanceSummary>('GET', '/weeks/balance')
};

// ─── Balance adjustments ─────────────────────────────────────────────────────

export const balance = {
	list: () => request<BalanceAdjustment[]>('GET', '/balance/adjustments'),

	create: async (body: { delta_ms: number; note?: string; effective_at?: number }): Promise<BalanceAdjustment> => {
		try {
			return await request<BalanceAdjustment>('POST', '/balance/adjustments', body);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const now = Date.now();
			const adj: BalanceAdjustment = {
				id: crypto.randomUUID(),
				delta_ms: body.delta_ms,
				note: body.note ?? '',
				effective_at: body.effective_at ?? now,
				created_at: now,
				updated_at: now
			};
			await db.balance_adjustments.put(adj);
			await enqueue('balance_adjustments', adj.id, 'upsert', adj);
			return adj;
		}
	},

	update: async (id: string, body: { delta_ms: number; note?: string; effective_at?: number }): Promise<BalanceAdjustment> => {
		try {
			return await request<BalanceAdjustment>('PUT', `/balance/adjustments/${id}`, body);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const existing = await db.balance_adjustments.get(id);
			if (!existing) throw e;
			const updated: BalanceAdjustment = { ...existing, ...body, updated_at: Date.now() };
			await db.balance_adjustments.put(updated);
			await enqueue('balance_adjustments', id, 'upsert', updated);
			return updated;
		}
	},

	delete: async (id: string): Promise<void> => {
		try {
			return await request<void>('DELETE', `/balance/adjustments/${id}`);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const existing = await db.balance_adjustments.get(id);
			await db.balance_adjustments.delete(id);
			await enqueue('balance_adjustments', id, 'delete', { id, updated_at: existing?.updated_at ?? Date.now() });
		}
	}
};

// ─── Settings ────────────────────────────────────────────────────────────────

export const settings = {
	current: () => request<Settings>('GET', '/settings'),
	history: () => request<Settings[]>('GET', '/settings/history'),

	upsert: async (body: {
		effective_from: string;
		hours_per_week: number;
		workdays_mask: number;
		timezone: string;
	}): Promise<Settings> => {
		try {
			return await request<Settings>('PUT', '/settings', body);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const now = Date.now();
			const s: Settings = {
				id: crypto.randomUUID(),
				...body,
				created_at: now,
				updated_at: now
			};
			await db.settings_history.put(s);
			await enqueue('settings_history', s.id, 'upsert', s);
			return s;
		}
	},

	update: async (id: string, body: {
		effective_from: string;
		hours_per_week: number;
		workdays_mask: number;
		timezone: string;
	}): Promise<Settings> => {
		try {
			return await request<Settings>('PUT', `/settings/history/${id}`, body);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			const existing = await db.settings_history.get(id);
			if (!existing) throw e;
			const updated: Settings = { ...existing, ...body, updated_at: Date.now() };
			await db.settings_history.put(updated);
			await enqueue('settings_history', id, 'upsert', updated);
			return updated;
		}
	},

	delete: async (id: string): Promise<void> => {
		try {
			return await request<void>('DELETE', `/settings/history/${id}`);
		} catch (e) {
			if (!isNetworkError(e)) throw e;
			await db.settings_history.delete(id);
			await enqueue('settings_history', id, 'delete', { id, updated_at: Date.now() });
		}
	}
};

// ─── Health ──────────────────────────────────────────────────────────────────

export const healthz = () =>
	fetch('/healthz').then((r) => r.ok);