using System.Collections.Concurrent;

namespace Campaign_Tracker.Server.ElectionCycles;

public sealed class InMemoryElectionCycleJobRepository : IElectionCycleJobRepository
{
    private const string StatusInSetup = "In Setup";

    private static readonly Dictionary<string, int> StatusSortOrder =
        new(StringComparer.OrdinalIgnoreCase)
        {
            [StatusInSetup] = 0,
            ["Ready"] = 1,
            ["In progress"] = 2,
            ["At risk"] = 3,
            ["Complete"] = 4,
            ["Blocked"] = 5,
        };

    private readonly ConcurrentDictionary<string, ElectionCycleJob> _jobs =
        new(StringComparer.OrdinalIgnoreCase);
    private readonly TimeProvider _timeProvider;

    // Seed data for kanban read model compatibility (Story 2.1).
    private readonly List<ElectionCycleJobAssignment> _seedAssignments =
    [
        new(
            JobId: "job-fair01-primary",
            JCode: "FAIR01",
            CycleId: "2026-primary",
            CycleName: "2026 Primary",
            Status: "Ready",
            IsActive: true),
        new(
            JobId: "job-lake02-primary",
            JCode: "LAKE02",
            CycleId: "2026-primary",
            CycleName: "2026 Primary",
            Status: "In progress",
            IsActive: true),
        new(
            JobId: "job-lake02-special",
            JCode: "LAKE02",
            CycleId: "2026-special",
            CycleName: "2026 Special",
            Status: "At risk",
            IsActive: true),
        new(
            JobId: "job-pine03-2024",
            JCode: "PINE03",
            CycleId: "2024-general",
            CycleName: "2024 General",
            Status: "Complete",
            IsActive: false),
    ];

    public InMemoryElectionCycleJobRepository(TimeProvider timeProvider)
    {
        _timeProvider = timeProvider;
    }

    // Constructor for tests that provide pre-seeded assignments.
    // Clears default seed data so tests control the exact dataset.
    public InMemoryElectionCycleJobRepository(
        IReadOnlyList<ElectionCycleJobAssignment> additionalAssignments,
        TimeProvider? timeProvider = null)
    {
        _timeProvider = timeProvider ?? TimeProvider.System;
        _seedAssignments.Clear();
        foreach (var a in additionalAssignments)
        {
            var job = new ElectionCycleJob(
                JobId: a.JobId,
                JCode: a.JCode,
                CycleId: a.CycleId,
                CycleName: a.CycleName,
                Status: a.Status,
                CreatedBy: "seed",
                CreatedAt: _timeProvider.GetUtcNow());
            _jobs[job.JobId] = job;
            _seedAssignments.Add(a);
        }
    }

    public Task<IReadOnlyList<ElectionCycleJobAssignment>> GetAllAsync(
        CancellationToken cancellationToken = default)
    {
        // Return seed assignments plus any dynamically created jobs not already in seeds.
        var jobIds = _seedAssignments.Select(a => a.JobId).ToHashSet(StringComparer.OrdinalIgnoreCase);
        var dynamicJobs = _jobs.Values
            .Where(j => !jobIds.Contains(j.JobId))
            .Select(MapToAssignment)
            .ToArray();
        var all = _seedAssignments.Concat(dynamicJobs).ToArray();
        return Task.FromResult<IReadOnlyList<ElectionCycleJobAssignment>>(all);
    }

    public Task<ElectionCycleJobSaveResult> CreateAsync(
        string jCode,
        string cycleId,
        string cycleName,
        string actorIdentity,
        CancellationToken cancellationToken = default)
    {
        var error = Validate(jCode, cycleId, cycleName);
        if (error is not null)
            return Task.FromResult(ElectionCycleJobSaveResult.Failure(error));

        var now = _timeProvider.GetUtcNow();
        var jobId = $"job-{jCode.ToLowerInvariant()}-{cycleId.ToLowerInvariant()}";

        // Idempotency: if a job with this composite key already exists, return it.
        if (_jobs.TryGetValue(jobId, out var existing))
            return Task.FromResult(ElectionCycleJobSaveResult.Success(existing));

        var job = new ElectionCycleJob(
            JobId: jobId,
            JCode: jCode.Trim().ToUpperInvariant(),
            CycleId: cycleId.Trim(),
            CycleName: cycleName.Trim(),
            Status: StatusInSetup,
            CreatedBy: actorIdentity,
            CreatedAt: now);

        _jobs[jobId] = job;
        return Task.FromResult(ElectionCycleJobSaveResult.Success(job));
    }

    private static string? Validate(string jCode, string cycleId, string cycleName)
    {
        if (string.IsNullOrWhiteSpace(jCode))
            return "Municipality identifier (JCode) is required.";

        if (string.IsNullOrWhiteSpace(cycleId))
            return "Cycle selection is required.";

        if (string.IsNullOrWhiteSpace(cycleName))
            return "Cycle name is required.";

        return null;
    }

    private static ElectionCycleJobAssignment MapToAssignment(ElectionCycleJob job) =>
        new(
            JobId: job.JobId,
            JCode: job.JCode,
            CycleId: job.CycleId,
            CycleName: job.CycleName,
            Status: job.Status,
            IsActive: true);
}