using MeterVault.Core.Domain;
using Microsoft.EntityFrameworkCore;

namespace MeterVault.Infrastructure.Persistence;

/// <summary>
/// Seeds sensible defaults (energy types, cost categories, base settings) on first run.
/// Idempotent — safe to call after every migration. Nothing here is hardcoded into the domain;
/// these are just starter rows the user can edit or delete (SDD FR-1).
/// </summary>
public static class DatabaseSeeder
{
    public static async Task SeedAsync(MeterVaultDbContext db, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(db);

        if (!await db.EnergyTypes.AnyAsync(cancellationToken).ConfigureAwait(false))
        {
            db.EnergyTypes.AddRange(DefaultEnergyTypes());
        }

        if (!await db.CostCategories.AnyAsync(cancellationToken).ConfigureAwait(false))
        {
            db.CostCategories.AddRange(DefaultCostCategories());
        }

        foreach (var (key, value) in DefaultSettings())
        {
            if (!await db.AppSettings.AnyAsync(s => s.Key == key, cancellationToken).ConfigureAwait(false))
            {
                db.AppSettings.Add(new AppSetting { Key = key, Value = value });
            }
        }

        await db.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
    }

    private static IEnumerable<EnergyType> DefaultEnergyTypes() =>
    [
        new() { Key = "electricity", DisplayName = "Strom", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter, Icon = "bolt", ColorHex = "#F6C445" },
        new() { Key = "water", DisplayName = "Wasser", BaseUnit = "m3", DefaultMode = MeterMode.CumulativeCounter, Icon = "water_drop", ColorHex = "#3B82F6" },
        new() { Key = "heating_oil", DisplayName = "Heizöl", BaseUnit = "L", DefaultMode = MeterMode.ConsumableBalance, Icon = "local_gas_station", ColorHex = "#B45309" },
        new() { Key = "gas", DisplayName = "Gas", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter, Icon = "gas_meter", ColorHex = "#EF4444" },
        new() { Key = "district_heat", DisplayName = "Fernwärme", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter, Icon = "thermostat", ColorHex = "#F97316" },
    ];

    private static IEnumerable<CostCategory> DefaultCostCategories() =>
    [
        new() { Name = "Heizung", ColorHex = "#B45309", Sort = 0 },
        new() { Name = "Strom", ColorHex = "#F6C445", Sort = 1 },
        new() { Name = "Wasser", ColorHex = "#3B82F6", Sort = 2 },
        new() { Name = "Pool Betrieb", ColorHex = "#14B8A6", Sort = 3 },
    ];

    private static IEnumerable<(string Key, string Value)> DefaultSettings() =>
    [
        ("currency", "\"EUR\""),
        ("locale", "\"en\""),
        ("timezone", "\"Europe/Berlin\""),
    ];
}