using System.Text.Json;
using ControlPlane.Core.Models;
using Microsoft.Extensions.Logging;
using Npgsql;

namespace ControlPlane.Core.Services;

/// <summary>
/// Persists build and release history to opcdb (Postgres).
/// Replaces the previous JSON-file implementation.
/// NpgsqlDataSource is singleton and manages the connection pool; this service is safe to register as singleton.
/// </summary>
public class BuildHistoryService(NpgsqlDataSource db, ILogger<BuildHistoryService> logger)
{
    // ── Builds ──────────────────────────────────────────────────────────────

    public async Task<BuildRecord> CreateBuildAsync(BuildKind kind, string target)
    {
        var record = new BuildRecord { Kind = kind, Target = target };

        await using var cmd = db.CreateCommand("""
            INSERT INTO build_record (id, kind, target, status, started_at, commit_sha, log)
            VALUES ($1, $2, $3, $4, $5, $6, $7)
            """);
        cmd.Parameters.AddWithValue(record.Id);
        cmd.Parameters.AddWithValue(record.Kind.ToString());
        cmd.Parameters.AddWithValue(record.Target);
        cmd.Parameters.AddWithValue(record.Status.ToString());
        cmd.Parameters.AddWithValue(record.StartedAt);
        cmd.Parameters.AddWithValue((object?)record.CommitSha ?? DBNull.Value);
        cmd.Parameters.AddWithValue(string.Empty);
        await cmd.ExecuteNonQueryAsync();

        return record;
    }

    public async Task CompleteBuildAsync(BuildRecord record, BuildStatus status, string? digest = null)
    {
        record.Status      = status;
        record.FinishedAt  = DateTimeOffset.UtcNow;
        record.DurationMs  = (int)(record.FinishedAt.Value - record.StartedAt).TotalMilliseconds;
        record.ImageDigest = digest;

        await using var cmd = db.CreateCommand("""
            UPDATE build_record
            SET status = $2, finished_at = $3, duration_ms = $4, image_digest = $5, commit_sha = $6, log = $7
            WHERE id = $1
            """);
        cmd.Parameters.AddWithValue(record.Id);
        cmd.Parameters.AddWithValue(record.Status.ToString());
        cmd.Parameters.AddWithValue(record.FinishedAt!.Value);
        cmd.Parameters.AddWithValue((object?)record.DurationMs ?? DBNull.Value);
        cmd.Parameters.AddWithValue((object?)record.ImageDigest ?? DBNull.Value);
        cmd.Parameters.AddWithValue((object?)record.CommitSha ?? DBNull.Value);
        cmd.Parameters.AddWithValue(string.Join('\n', record.Log));
        await cmd.ExecuteNonQueryAsync();
    }

    public async Task AppendBuildLogAsync(BuildRecord record, string line)
    {
        record.Log.Add(line);
        // Flush to Postgres every 20 lines — keeps the live log queryable without hammering the DB
        if (record.Log.Count % 20 == 0)
            await FlushLogAsync(record);
    }

    private async Task FlushLogAsync(BuildRecord record)
    {
        await using var cmd = db.CreateCommand("UPDATE build_record SET log = $2 WHERE id = $1");
        cmd.Parameters.AddWithValue(record.Id);
        cmd.Parameters.AddWithValue(string.Join('\n', record.Log));
        await cmd.ExecuteNonQueryAsync();
    }

    public async Task<List<BuildRecord>> GetBuildsAsync()
    {
        var result = new List<BuildRecord>();

        await using var cmd = db.CreateCommand("""
            SELECT id, kind, target, status, started_at, finished_at, duration_ms, image_digest, commit_sha, log
            FROM build_record
            ORDER BY started_at DESC
            LIMIT 100
            """);
        await using var reader = await cmd.ExecuteReaderAsync();
        while (await reader.ReadAsync())
        {
            var logText = reader.IsDBNull(9) ? "" : reader.GetString(9);
            result.Add(new BuildRecord
            {
                Id          = reader.GetString(0),
                Kind        = Enum.Parse<BuildKind>(reader.GetString(1)),
                Target      = reader.GetString(2),
                Status      = Enum.Parse<BuildStatus>(reader.GetString(3)),
                StartedAt   = reader.GetFieldValue<DateTimeOffset>(4),
                FinishedAt  = reader.IsDBNull(5) ? null : reader.GetFieldValue<DateTimeOffset>(5),
                DurationMs  = reader.IsDBNull(6) ? null : reader.GetInt32(6),
                ImageDigest = reader.IsDBNull(7) ? null : reader.GetString(7),
                CommitSha   = reader.IsDBNull(8) ? null : reader.GetString(8),
                Log         = logText.Length == 0 ? [] : [.. logText.Split('\n')],
            });
        }

        return result;
    }

    // ── Builds by SHA ────────────────────────────────────────────────────────

    /// <summary>Returns all build records whose <c>commit_sha</c> exactly matches <paramref name="sha"/>.</summary>
    public async Task<List<BuildRecord>> GetBuildsByShaAsync(string sha)
    {
        var result = new List<BuildRecord>();

        await using var cmd = db.CreateCommand("""
            SELECT id, kind, target, status, started_at, finished_at, duration_ms, image_digest, commit_sha, log
            FROM build_record
            WHERE commit_sha = $1
            ORDER BY started_at DESC
            """);
        cmd.Parameters.AddWithValue(sha);
        await using var reader = await cmd.ExecuteReaderAsync();
        while (await reader.ReadAsync())
        {
            var logText = reader.IsDBNull(9) ? "" : reader.GetString(9);
            result.Add(new BuildRecord
            {
                Id          = reader.GetString(0),
                Kind        = Enum.Parse<BuildKind>(reader.GetString(1)),
                Target      = reader.GetString(2),
                Status      = Enum.Parse<BuildStatus>(reader.GetString(3)),
                StartedAt   = reader.GetFieldValue<DateTimeOffset>(4),
                FinishedAt  = reader.IsDBNull(5) ? null : reader.GetFieldValue<DateTimeOffset>(5),
                DurationMs  = reader.IsDBNull(6) ? null : reader.GetInt32(6),
                ImageDigest = reader.IsDBNull(7) ? null : reader.GetString(7),
                CommitSha   = reader.IsDBNull(8) ? null : reader.GetString(8),
                Log         = logText.Length == 0 ? [] : [.. logText.Split('\n')],
            });
        }

        return result;
    }

    // ── Releases ────────────────────────────────────────────────────────────

    public async Task<ReleaseRecord> CreateReleaseAsync(string environment, string imageName, string? commitSha = null)
    {
        var record = new ReleaseRecord { Environment = environment, ImageName = imageName, CommitSha = commitSha };

        await using var cmd = db.CreateCommand("""
            INSERT INTO release_record (id, environment, image_name, status, started_at, opc_numbers, commit_sha)
            VALUES ($1, $2, $3, $4, $5, $6, $7)
            """);
        cmd.Parameters.AddWithValue(record.Id);
        cmd.Parameters.AddWithValue(record.Environment);
        cmd.Parameters.AddWithValue(record.ImageName);
        cmd.Parameters.AddWithValue(record.Status.ToString());
        cmd.Parameters.AddWithValue(record.StartedAt);
        cmd.Parameters.Add(new NpgsqlParameter<string[]> { TypedValue = [.. record.OpcNumbers] });
        cmd.Parameters.AddWithValue((object?)record.CommitSha ?? DBNull.Value);
        await cmd.ExecuteNonQueryAsync();

        return record;
    }

    public async Task UpdateReleaseAsync(ReleaseRecord record)
    {
        record.FinishedAt = DateTimeOffset.UtcNow;

        await using var conn = await db.OpenConnectionAsync();
        await using var tx   = await conn.BeginTransactionAsync();

        await using var upd = new NpgsqlCommand("""
            UPDATE release_record SET status = $2, finished_at = $3, opc_numbers = $4, commit_sha = $5 WHERE id = $1
            """, conn, tx);
        upd.Parameters.AddWithValue(record.Id);
        upd.Parameters.AddWithValue(record.Status.ToString());
        upd.Parameters.AddWithValue(record.FinishedAt!.Value);
        upd.Parameters.Add(new NpgsqlParameter<string[]> { TypedValue = [.. record.OpcNumbers] });
        upd.Parameters.AddWithValue((object?)record.CommitSha ?? DBNull.Value);
        await upd.ExecuteNonQueryAsync();

        // Replace tenant results wholesale on each update
        await using var del = new NpgsqlCommand(
            "DELETE FROM release_tenant_result WHERE release_id = $1", conn, tx);
        del.Parameters.AddWithValue(record.Id);
        await del.ExecuteNonQueryAsync();

        foreach (var t in record.Tenants)
        {
            await using var ins = new NpgsqlCommand("""
                INSERT INTO release_tenant_result (release_id, subdomain, container_name, success, error)
                VALUES ($1, $2, $3, $4, $5)
                """, conn, tx);
            ins.Parameters.AddWithValue(record.Id);
            ins.Parameters.AddWithValue(t.Subdomain);
            ins.Parameters.AddWithValue(t.ContainerName);
            ins.Parameters.AddWithValue(t.Success);
            ins.Parameters.AddWithValue((object?)t.Error ?? DBNull.Value);
            await ins.ExecuteNonQueryAsync();
        }

        await tx.CommitAsync();
    }

    public async Task<List<ReleaseRecord>> GetReleasesAsync()
    {
        var ordered = new List<ReleaseRecord>();
        var lookup  = new Dictionary<string, ReleaseRecord>();

        await using var cmd = db.CreateCommand("""
            SELECT id, environment, image_name, status, started_at, finished_at, opc_numbers, commit_sha
            FROM release_record
            ORDER BY started_at DESC
            LIMIT 50
            """);
        await using (var reader = await cmd.ExecuteReaderAsync())
        {
            while (await reader.ReadAsync())
            {
                var r = new ReleaseRecord
                {
                    Id          = reader.GetString(0),
                    Environment = reader.GetString(1),
                    ImageName   = reader.GetString(2),
                    Status      = Enum.Parse<ReleaseStatus>(reader.GetString(3)),
                    StartedAt   = reader.GetFieldValue<DateTimeOffset>(4),
                    FinishedAt  = reader.IsDBNull(5) ? null : reader.GetFieldValue<DateTimeOffset>(5),
                    OpcNumbers  = reader.IsDBNull(6) ? [] : [.. reader.GetFieldValue<string[]>(6)],
                    CommitSha   = reader.IsDBNull(7) ? null : reader.GetString(7),
                };
                ordered.Add(r);
                lookup[r.Id] = r;
            }
        }

        if (lookup.Count == 0) return [];

        // Load all tenant results for the fetched release IDs in one query
        await using var cmd2 = db.CreateCommand("""
            SELECT release_id, subdomain, container_name, success, error
            FROM release_tenant_result
            WHERE release_id = ANY($1)
            """);
        cmd2.Parameters.Add(new NpgsqlParameter<string[]> { TypedValue = [.. lookup.Keys] });
        await using var reader2 = await cmd2.ExecuteReaderAsync();
        while (await reader2.ReadAsync())
        {
            if (lookup.TryGetValue(reader2.GetString(0), out var r))
                r.Tenants.Add(new TenantReleaseResult
                {
                    Subdomain     = reader2.GetString(1),
                    ContainerName = reader2.GetString(2),
                    Success       = reader2.GetBoolean(3),
                    Error         = reader2.IsDBNull(4) ? null : reader2.GetString(4),
                });
        }

        return ordered;
    }

    /// <summary>
    /// Returns the most recent succeeded release for <paramref name="environment"/>, or null if none exists.
    /// Used to calculate the OPC ticket delta between releases (previousSha..currentSha).
    /// </summary>
    public async Task<ReleaseRecord?> GetLastSuccessfulReleaseForEnvAsync(string environment)
    {
        await using var cmd = db.CreateCommand("""
            SELECT id, environment, image_name, status, started_at, finished_at, opc_numbers, commit_sha
            FROM release_record
            WHERE environment = $1 AND status = 'Succeeded'
            ORDER BY started_at DESC
            LIMIT 1
            """);
        cmd.Parameters.AddWithValue(environment);
        await using var reader = await cmd.ExecuteReaderAsync();
        if (!await reader.ReadAsync()) return null;
        return new ReleaseRecord
        {
            Id          = reader.GetString(0),
            Environment = reader.GetString(1),
            ImageName   = reader.GetString(2),
            Status      = Enum.Parse<ReleaseStatus>(reader.GetString(3)),
            StartedAt   = reader.GetFieldValue<DateTimeOffset>(4),
            FinishedAt  = reader.IsDBNull(5) ? null : reader.GetFieldValue<DateTimeOffset>(5),
            OpcNumbers  = reader.IsDBNull(6) ? [] : [.. reader.GetFieldValue<string[]>(6)],
            CommitSha   = reader.IsDBNull(7) ? null : reader.GetString(7),
        };
    }
}