using Microsoft.Extensions.Hosting;

namespace Tau.Acuvim.Portal.Configuration;

public static class ConnectionStringResolver
{
    public sealed record Resolution(string ConnectionString, string Source);

    // Precedence:
    //   1. Database.ConnectionString (explicit) — always wins.
    //   2. Database.AutoProvisionLocalTimescaleDb == true AND env != Production — build from TimescaleDb block.
    //   3. Otherwise — throw. Production must supply an explicit connection string.
    public static Resolution Resolve(
        DatabaseOptions database,
        TimescaleDbOptions timescale,
        IHostEnvironment env)
    {
        if (!string.IsNullOrWhiteSpace(database.ConnectionString))
        {
            return new Resolution(database.ConnectionString, "Database:ConnectionString");
        }

        if (database.AutoProvisionLocalTimescaleDb && !env.IsProduction())
        {
            var built =
                $"Host={timescale.Host};Port={timescale.Port};Database={timescale.Database};" +
                $"Username={timescale.Username};Password={timescale.Password}";
            return new Resolution(built, "auto-provision from TimescaleDb section");
        }

        if (database.AutoProvisionLocalTimescaleDb && env.IsProduction())
        {
            throw new InvalidOperationException(
                "AutoProvisionLocalTimescaleDb=true is not permitted in Production. " +
                "Set Database:ConnectionString explicitly via env var or secret.");
        }

        throw new InvalidOperationException(
            "No database connection string available. Set Database:ConnectionString, " +
            "or enable Database:AutoProvisionLocalTimescaleDb in a non-Production environment.");
    }
}