/** Service for bus stop-related API calls */
import { supabase } from '@/supabase'
import type { BusStop, Route } from '@/types'

// Map JS getDay() (0=Sun,6=Sat) to Spanish day names used in dias_operacion
const DAY_MAP: Record<number, string> = {
    0: 'domingo',
    1: 'lunes',
    2: 'martes',
    3: 'miercoles',
    4: 'jueves',
    5: 'viernes',
    6: 'sabado'
}

/** Convert "HH:MM:SS" time string to total minutes since midnight */
function timeToMinutes(t: string): number {
    const parts = t.split(':')
    return parseInt(parts[0] || '0') * 60 + parseInt(parts[1] || '0')
}

/** Convert total minutes since midnight back to "HH:MM" string */
function minutesToTime(m: number): string {
    const safeM = ((m % 1440) + 1440) % 1440  // wrap around midnight
    const h = Math.floor(safeM / 60)
    const min = safeM % 60
    return `${h.toString().padStart(2, '0')}:${min.toString().padStart(2, '0')}`
}

export interface BusArrival {
    routeName: string
    routeId: string
    arrivalTime: string         // "HH:MM" when bus arrives at this stop
    waitMinutes: number | null  // null = no GPS, raw schedule shown
    hasGps: boolean
    departureTime: string       // "HH:MM" when bus departs origin
    alreadyPassed: boolean      // true if bus has already passed this stop
}

export const busStopsService = {
    /** Get all bus stops */
    async getAllBusStops(): Promise<BusStop[]> {
        const { data, error } = await supabase.from('bus_stops').select('id, name, latitude, longitude, city, address, stop_type, has_shelter, has_seating, is_accessible, created_at, updated_at')
        if (error) throw new Error(error.message)
        return data as BusStop[]
    },

    /** Get a single bus stop by ID */
    async getBusStopById(id: string): Promise<BusStop> {
        const { data, error } = await supabase.from('bus_stops').select('id, name, latitude, longitude, city, address, stop_type, has_shelter, has_seating, is_accessible, created_at, updated_at').eq('id', id).single()
        if (error) throw new Error(error.message)
        return data as BusStop
    },

    /** Get all routes passing through a bus stop */
    async getBusStopRoutes(stopId: string): Promise<Route[]> {
        const { data, error } = await supabase
            .from('route_stops')
            .select('routes(*)')
            .eq('stop_id', stopId)

        if (error) throw new Error(error.message)
        // Extract the nested strictly typed route object automatically connected by Supabase relationships
        return (data || []).map((row: any) => row.routes) as Route[]
    },

    /**
     * Real-time bus arrival calculator for a specific stop.
     *
     * Logic:
     *  1. Get all routes through this stop + their travel_time_minutes
     *  2. Get route's origin_stop_id → get its travel_time_minutes as the "base"
     *  3. Effective travel time = stop.travel_time - origin.travel_time  (always >= 0)
     *  4. arrivalAtStop = departure_time + effective_travel_time
     *  5. With GPS: filter to future buses, return wait minutes
     *     Without GPS (option A): show raw schedule times for today
     */
    async getNextBusesForStop(stopId: string, userLat?: number, userLng?: number): Promise<BusArrival[]> {
        const hasGps = userLat !== undefined && userLng !== undefined

        // ── STEP 1: Get route_stops entry for THIS stop on every route it belongs to ──
        const { data: routeStopsData, error: rsError } = await supabase
            .from('route_stops')
            .select('route_id, travel_time_minutes, stop_delay_minutes')
            .eq('stop_id', stopId)

        if (rsError) throw new Error(rsError.message)
        if (!routeStopsData || routeStopsData.length === 0) return []

        const routeIds = routeStopsData.map((rs: any) => rs.route_id)

        // Build a lookup: routeId → raw travel_time_minutes of THIS stop
        const rawTravelTimeMap: Record<string, number> = {}
        for (const rs of routeStopsData as any[]) {
            rawTravelTimeMap[rs.route_id] = (rs.travel_time_minutes || 0) + (rs.stop_delay_minutes || 0)
        }

        // ── STEP 2: Get route metadata including origin_stop_id ──
        const { data: routesData, error: routesError } = await supabase
            .from('routes')
            .select('id, name, origin_stop_id')
            .in('id', routeIds)

        if (routesError) throw new Error(routesError.message)

        const routeNameMap: Record<string, string> = {}
        const originStopIdMap: Record<string, string | null> = {}  // routeId → origin_stop_id
        for (const r of (routesData || []) as any[]) {
            routeNameMap[r.id] = r.name
            originStopIdMap[r.id] = r.origin_stop_id || null
        }

        // ── STEP 3: Get travel_time_minutes of the origin stop for each route ──
        // This gives us the "base offset" so we can normalize travel times correctly.
        // If origin_stop has travel_time=5 and user's stop has travel_time=30, effective = 25 min.
        const originStopIds = [...new Set(Object.values(originStopIdMap).filter(Boolean))] as string[]
        const originTravelTimeMap: Record<string, number> = {}  // routeId → origin stop travel_time

        if (originStopIds.length > 0) {
            // Fetch travel_time_minutes for origin stops across all relevant routes
            const { data: originRsData } = await supabase
                .from('route_stops')
                .select('route_id, stop_id, travel_time_minutes')
                .in('route_id', routeIds)
                .in('stop_id', originStopIds)

            for (const ors of (originRsData || []) as any[]) {
                // Match route to its origin stop
                if (originStopIdMap[ors.route_id] === ors.stop_id) {
                    originTravelTimeMap[ors.route_id] = ors.travel_time_minutes || 0
                }
            }
        }

        // Compute EFFECTIVE travel time = user's stop travel_time - origin stop travel_time
        // This is always >= 0 if the data is correct (origin is before the user's stop)
        const effectiveTravelTimeMap: Record<string, number> = {}
        for (const routeId of routeIds) {
            const rawTime = rawTravelTimeMap[routeId] ?? 0
            const originTime = originTravelTimeMap[routeId] ?? 0
            effectiveTravelTimeMap[routeId] = Math.max(0, rawTime - originTime)
        }


        // ── STEP 3: Get today's schedules ──
        const now = new Date()
        const todayDay = DAY_MAP[now.getDay()]
        const nowMinutes = now.getHours() * 60 + now.getMinutes()

        const { data: schedulesData, error: schError } = await supabase
            .from('bus_schedules')
            .select('route_id, departure_time, dias_operacion')
            .in('route_id', routeIds)
            .eq('is_published', true)
            .order('departure_time', { ascending: true })

        if (schError) throw new Error(schError.message)
        if (!schedulesData || schedulesData.length === 0) return []

        // ── STEP 4: Calculate arrival time for each schedule at THIS stop ──
        const arrivals: BusArrival[] = []

        for (const sched of schedulesData as any[]) {
            // Check if this schedule runs today
            const diasOp: string[] = sched.dias_operacion || []
            if (!todayDay || !diasOp.includes(todayDay)) continue


            const depMinutes = timeToMinutes(sched.departure_time)
            const travelMins = effectiveTravelTimeMap[sched.route_id] ?? 0
            const arrivalMinutes = depMinutes + travelMins


            // Handle midnight crossover (e.g. departure 23:50 + 20min travel = 00:10 next day)
            const arrivalMinutesNormalized = arrivalMinutes % 1440

            const alreadyPassed = arrivalMinutesNormalized < nowMinutes
            const waitMinutes = hasGps ? (arrivalMinutesNormalized - nowMinutes) : null

            // Without GPS (option A): show all future arrivals as raw times
            // With GPS: only show buses that haven't passed yet
            if (hasGps && alreadyPassed) continue

            // Skip buses more than 3 hours in the future to avoid showing the whole day
            if (hasGps && waitMinutes !== null && waitMinutes > 180) continue

            // Without GPS: skip past arrivals but show up to next 3 hours anyway
            if (!hasGps && alreadyPassed && Math.abs(arrivalMinutesNormalized - nowMinutes) > 10) continue

            arrivals.push({
                routeName: routeNameMap[sched.route_id] || 'Ruta desconocida',
                routeId: sched.route_id,
                arrivalTime: minutesToTime(arrivalMinutesNormalized),
                departureTime: minutesToTime(depMinutes),
                waitMinutes,
                hasGps,
                alreadyPassed
            })
        }

        // Sort by arrival time ascending, return first 8
        arrivals.sort((a, b) => {
            const aMin = timeToMinutes(a.arrivalTime)
            const bMin = timeToMinutes(b.arrivalTime)
            return aMin - bMin
        })

        return arrivals.slice(0, 8)
    },

    /**
     * @deprecated Use getNextBusesForStop instead.
     * Kept for compatibility — calls the real engine without GPS context.
     */
    async getNextBusArrivals(stopId: string): Promise<{ routeName: string; arrivalTime: string }[]> {
        const real = await this.getNextBusesForStop(stopId)
        return real.map(a => ({ routeName: a.routeName, arrivalTime: a.arrivalTime }))
    },

    /** Create a new bus stop (Admin) */
    async createBusStop(currentData: import('@/types').BusStopCreate): Promise<BusStop> {
        const { data, error } = await supabase
            .from('bus_stops')
            .insert([currentData])
            .select()
            .single()

        if (error) throw new Error(error.message)
        return data as BusStop
    },

    /** Update a bus stop (Admin) */
    async updateBusStop(id: string, currentData: import('@/types').BusStopUpdate): Promise<BusStop> {
        const { data, error } = await supabase
            .from('bus_stops')
            .update(currentData)
            .eq('id', id)
            .select()
            .single()

        if (error) throw new Error(error.message)
        return data as BusStop
    },

    /** Delete a bus stop (Admin) */
    async deleteBusStop(id: string): Promise<void> {
        const { error } = await supabase.from('bus_stops').delete().eq('id', id)
        if (error) throw new Error(error.message)
    }
}
