using Microsoft.Extensions.Configuration;

namespace MeetingAssistant.LaunchProfiles;

public interface ILaunchProfileOptionsProvider
{
    LaunchProfile GetRequiredProfile(string? name);

    IReadOnlyList<LaunchProfile> GetProfiles();

    IReadOnlyList<LaunchProfileHotkey> GetHotkeys();
}

public sealed record LaunchProfile(string Name, MeetingAssistantOptions Options);

public enum LaunchProfileHotkeyAction
{
    ToggleRecording,
    AbortRecording,
    CaptureScreenshot
}

public sealed record LaunchProfileHotkey(
    string ProfileName,
    string Hotkey,
    LaunchProfileHotkeyAction Action);

public sealed class ConfigurationLaunchProfileOptionsProvider : ILaunchProfileOptionsProvider
{
    public const string DefaultProfileName = "default";
    private static readonly HotkeyDescriptor[] HotkeyDescriptors =
    [
        new("Hotkey:Toggle", options => options.Hotkey.Toggle, LaunchProfileHotkeyAction.ToggleRecording),
        new("Hotkey:Abort", options => options.Hotkey.Abort, LaunchProfileHotkeyAction.AbortRecording),
        new("Screenshots:Hotkey", options => options.Screenshots.Hotkey, LaunchProfileHotkeyAction.CaptureScreenshot)
    ];

    private readonly IConfiguration configuration;

    public ConfigurationLaunchProfileOptionsProvider(IConfiguration configuration)
    {
        this.configuration = configuration;
    }

    public LaunchProfile GetRequiredProfile(string? name)
    {
        var profileName = NormalizeProfileName(name);
        var options = BindDefaultOptions();
        if (profileName.Equals(DefaultProfileName, StringComparison.OrdinalIgnoreCase))
        {
            return new LaunchProfile(DefaultProfileName, options);
        }

        var profileSection = GetProfilesSection().GetSection(profileName);
        if (!profileSection.Exists())
        {
            throw new KeyNotFoundException($"Launch profile '{profileName}' is not configured.");
        }

        profileSection.Bind(options);
        ApplyArrayOverrides(profileSection, options);
        return new LaunchProfile(profileName, options);
    }

    public IReadOnlyList<LaunchProfileHotkey> GetHotkeys()
    {
        var hotkeys = GetProfileNames()
            .SelectMany(CreateHotkeys)
            .ToList();
        var duplicate = hotkeys
            .GroupBy(hotkey => hotkey.Hotkey.Trim(), StringComparer.OrdinalIgnoreCase)
            .FirstOrDefault(group => group.Count() > 1);
        if (duplicate is not null)
        {
            throw new InvalidOperationException(
                $"Launch profile hotkey '{duplicate.Key}' is configured more than once for profiles {string.Join(", ", duplicate.Select(hotkey => $"{hotkey.ProfileName}:{hotkey.Action}"))}.");
        }

        return hotkeys;
    }

    public IReadOnlyList<LaunchProfile> GetProfiles()
    {
        return GetProfileNames()
            .Select(GetRequiredProfile)
            .ToList();
    }

    private IEnumerable<LaunchProfileHotkey> CreateHotkeys(string profileName)
    {
        var profile = GetRequiredProfile(profileName);
        var isDefaultProfile = profileName.Equals(DefaultProfileName, StringComparison.OrdinalIgnoreCase);
        var profileSection = isDefaultProfile
            ? null
            : GetProfilesSection().GetSection(profileName);

        foreach (var descriptor in HotkeyDescriptors)
        {
            var hotkey = descriptor.GetValue(profile.Options);
            if (ShouldRegisterHotkey(isDefaultProfile, profileSection?.GetSection(descriptor.SectionPath)) &&
                !string.IsNullOrWhiteSpace(hotkey))
            {
                yield return new LaunchProfileHotkey(
                    profile.Name,
                    hotkey,
                    descriptor.Action);
            }
        }
    }

    private static bool ShouldRegisterHotkey(bool isDefaultProfile, IConfigurationSection? profileHotkeySection)
    {
        return isDefaultProfile || profileHotkeySection?.Exists() == true;
    }

    private IReadOnlyList<string> GetProfileNames()
    {
        return new[] { DefaultProfileName }
            .Concat(GetProfilesSection()
                .GetChildren()
                .Select(section => section.Key)
                .Where(key => !key.Equals(DefaultProfileName, StringComparison.OrdinalIgnoreCase)))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToList();
    }

    private MeetingAssistantOptions BindDefaultOptions()
    {
        var options = new MeetingAssistantOptions();
        GetRootSection().Bind(options);
        return options;
    }

    private IConfigurationSection GetRootSection()
    {
        return configuration.GetSection("MeetingAssistant");
    }

    private IConfigurationSection GetProfilesSection()
    {
        return GetRootSection().GetSection("LaunchProfiles");
    }

    private static string NormalizeProfileName(string? name)
    {
        return string.IsNullOrWhiteSpace(name) ||
            name.Equals(DefaultProfileName, StringComparison.OrdinalIgnoreCase)
            ? DefaultProfileName
            : name.Trim();
    }

    private static void ApplyArrayOverrides(
        IConfigurationSection profileSection,
        MeetingAssistantOptions options)
    {
        var autoDetectLanguages = ReadArrayOverride(profileSection.GetSection("AzureSpeech:AutoDetectLanguages"));
        if (autoDetectLanguages is not null)
        {
            options.AzureSpeech.AutoDetectLanguages = autoDetectLanguages;
        }

        var funAsrChunkSize = ReadIntArrayOverride(profileSection.GetSection("FunAsr:ChunkSize"));
        if (funAsrChunkSize is not null)
        {
            options.FunAsr.ChunkSize = funAsrChunkSize;
        }
    }

    private static string[]? ReadArrayOverride(IConfigurationSection section)
    {
        if (!section.Exists())
        {
            return null;
        }

        return section
            .GetChildren()
            .OrderBy(child => int.TryParse(child.Key, out var index) ? index : int.MaxValue)
            .Select(child => child.Value)
            .Where(value => !string.IsNullOrWhiteSpace(value))
            .Select(value => value!)
            .ToArray();
    }

    private static int[]? ReadIntArrayOverride(IConfigurationSection section)
    {
        if (!section.Exists())
        {
            return null;
        }

        return section
            .GetChildren()
            .OrderBy(child => int.TryParse(child.Key, out var index) ? index : int.MaxValue)
            .Select(child => int.TryParse(child.Value, out var value) ? value : (int?)null)
            .Where(value => value.HasValue)
            .Select(value => value!.Value)
            .ToArray();
    }

    private sealed record HotkeyDescriptor(
        string SectionPath,
        Func<MeetingAssistantOptions, string> GetValue,
        LaunchProfileHotkeyAction Action);
}