using MeterVault.Core.Domain;
using MeterVault.Infrastructure.Costing;
using MeterVault.Infrastructure.Dashboard;
using MeterVault.Infrastructure.Ingestion;
using MeterVault.Infrastructure.Normalization;
using MeterVault.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;

namespace MeterVault.App.Api;

/// <summary>Request/response contracts for the REST API (SDD §9).</summary>
public sealed record ReadingPush(int MeterId, DateTimeOffset Time, double Value);

public sealed record EventPush(int MeterId, DateTimeOffset Time, MeterEventType Type,
    double? Amount, double? PrevValue, double? NewValue, string? Unit, string? Notes);

public sealed record TariffPush(TariffScope ScopeType, int? ScopeId, TariffComponent Component,
    double Value, string Unit, DateOnly ValidFrom, DateOnly? ValidTo);

public sealed record IngestResult(int Written, int Updated, int Rejected);

/// <summary>Maps the versioned REST API. All endpoints require a valid API key (SDD §9).</summary>
public static class ApiEndpoints
{
    public static IEndpointRouteBuilder MapMeterVaultApi(this IEndpointRouteBuilder app)
    {
        var api = app.MapGroup("/api/v1").AddEndpointFilter<ApiKeyFilter>().WithTags("MeterVault");

        api.MapPost("/readings", async (ReadingPush[] readings, IngestionService ingestion, CancellationToken ct) =>
        {
            int written = 0, updated = 0, rejected = 0;
            foreach (var r in readings)
            {
                switch (await ingestion.IngestByMeterAsync(r.MeterId, r.Time, r.Value, ct))
                {
                    case IngestionOutcome.Written: written++; break;
                    case IngestionOutcome.Updated: updated++; break;
                    case IngestionOutcome.RejectedDecrease: rejected++; break;
                    default: break;
                }
            }

            return Results.Ok(new IngestResult(written, updated, rejected));
        }).WithSummary("Ingest one or more readings (idempotent). Lets Home Assistant push.");

        api.MapGet("/meters", async (MeterVaultDbContext db, CancellationToken ct) =>
            Results.Ok(await db.Meters.AsNoTracking()
                .Select(m => new { m.Id, m.Name, m.EnergyTypeId, Mode = m.Mode.ToString(), m.Unit, m.IsActive })
                .ToListAsync(ct)));

        api.MapGet("/energy-types", async (MeterVaultDbContext db, CancellationToken ct) =>
            Results.Ok(await db.EnergyTypes.AsNoTracking()
                .Select(t => new { t.Id, t.Key, t.DisplayName, t.BaseUnit, Mode = t.DefaultMode.ToString() })
                .ToListAsync(ct)));

        api.MapGet("/consumption", async (int meter, DateTimeOffset from, DateTimeOffset to,
            CostService cost, CancellationToken ct) =>
        {
            var buckets = await cost.GetMeterCostsAsync(meter, from, to, CostBucket.Month, ct);
            return Results.Ok(buckets.Select(b => new { b.Period, b.Consumption, b.Generation }));
        }).WithSummary("Normalized monthly consumption/generation for a meter.");

        api.MapGet("/cost", async (int meter, DateTimeOffset from, DateTimeOffset to,
            CostService cost, CancellationToken ct) =>
            Results.Ok(await cost.GetMeterCostsAsync(meter, from, to, CostBucket.Month, ct)));

        api.MapGet("/dashboard/summary", async (DashboardService dashboard, CancellationToken ct) =>
            Results.Ok(await dashboard.GetSummaryAsync(DateOnly.FromDateTime(DateTime.UtcNow), ct)));

        api.MapPost("/events", async (EventPush push, MeterVaultDbContext db,
            NormalizationService normalization, CancellationToken ct) =>
        {
            db.MeterEvents.Add(new MeterEvent
            {
                MeterId = push.MeterId,
                Time = push.Time,
                EventType = push.Type,
                Amount = push.Amount,
                PrevValue = push.PrevValue,
                NewValue = push.NewValue,
                Unit = push.Unit,
                Notes = push.Notes,
            });
            await db.SaveChangesAsync(ct);
            await normalization.RecomputeMeterAsync(push.MeterId, null, ct);
            await db.SaveChangesAsync(ct);
            return Results.Ok();
        }).WithSummary("Record a delivery / swap / tank level / correction and recompute the meter.");

        api.MapGet("/tariffs", async (MeterVaultDbContext db, CancellationToken ct) =>
            Results.Ok(await db.Tariffs.AsNoTracking().OrderBy(t => t.ValidFrom).ToListAsync(ct)));

        api.MapPost("/tariffs", async (TariffPush push, MeterVaultDbContext db, CancellationToken ct) =>
        {
            var tariff = new Tariff
            {
                ScopeType = push.ScopeType,
                ScopeId = push.ScopeId,
                Component = push.Component,
                Value = push.Value,
                Unit = push.Unit,
                ValidFrom = push.ValidFrom,
                ValidTo = push.ValidTo,
            };
            db.Tariffs.Add(tariff);
            await db.SaveChangesAsync(ct);
            return Results.Created($"/api/v1/tariffs/{tariff.Id}", new { tariff.Id });
        });

        api.MapGet("/sources/status", async (MeterVaultDbContext db, CancellationToken ct) =>
            Results.Ok(await db.MeterSources.AsNoTracking()
                .Select(s => new { s.Id, s.MeterId, Type = s.SourceType.ToString(), s.IsEnabled, s.LastSeenAt, s.LastValue, s.LastStatus })
                .ToListAsync(ct)));

        return app;
    }
}