using System.Diagnostics;
using System.Text.Json;
using System.Text.RegularExpressions;
using MeetingAssistant.Speakers;
using Microsoft.EntityFrameworkCore;
using YamlDotNet.Core;
using YamlDotNet.Serialization;
using YamlDotNet.Serialization.NamingConventions;

namespace MeetingAssistant.Workflow;

public sealed class WorkflowRulesEditorTools
{
    private static readonly IDeserializer YamlDeserializer = new DeserializerBuilder()
        .WithNamingConvention(UnderscoredNamingConvention.Instance)
        .IgnoreUnmatchedProperties()
        .Build();
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
    {
        WriteIndented = true
    };

    private readonly string? rulesPath;
    private readonly SpeakerIdentificationOptions speakerOptions;
    private readonly IDbContextFactory<SpeakerIdentityDbContext>? dbContextFactory;
    private readonly IWorkflowRulesEditorSamplePlaybackQueue? samplePlaybackQueue;

    public WorkflowRulesEditorTools(
        MeetingAssistantOptions options,
        IDbContextFactory<SpeakerIdentityDbContext>? dbContextFactory = null,
        IWorkflowRulesEditorSamplePlaybackQueue? samplePlaybackQueue = null)
    {
        rulesPath = WorkflowRulesPathResolver.Resolve(options.Automation.RulesPath);
        speakerOptions = options.SpeakerIdentification;
        this.dbContextFactory = dbContextFactory;
        this.samplePlaybackQueue = samplePlaybackQueue;
    }

    public async Task<string> ReadRules(int? from = null, int? to = null)
    {
        if (rulesPath is null)
        {
            return "Workflow rules file is not configured.";
        }

        if (!File.Exists(rulesPath))
        {
            return "";
        }

        return ReadLines(await File.ReadAllTextAsync(rulesPath), from, to);
    }

    public async Task<string> WriteRules(string yaml)
    {
        if (rulesPath is null)
        {
            return "Refused: workflow rules file is not configured.";
        }

        if (yaml is null)
        {
            return "Refused: yaml must not be null.";
        }

        var validation = ValidateYaml(yaml);
        if (validation is not null)
        {
            return validation;
        }

        Directory.CreateDirectory(Path.GetDirectoryName(rulesPath)!);
        await File.WriteAllTextAsync(rulesPath, yaml);
        return rulesPath;
    }

    public async Task<string> Search(string keywords)
    {
        if (rulesPath is null || string.IsNullOrWhiteSpace(keywords) || !File.Exists(rulesPath))
        {
            return "";
        }

        var rgResult = await RunRipgrepAsync(rulesPath, keywords);
        return rgResult is not null
            ? FormatRipgrepJson(rgResult)
            : SearchWithRegexFallback(rulesPath, keywords);
    }

    public async Task<string> SearchIdentities(string? query = null, int limit = 25)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var identities = await LoadIdentities(context)
                .OrderBy(identity => identity.CanonicalName ?? "")
                .ThenBy(identity => identity.Id)
                .ToListAsync();
            if (!string.IsNullOrWhiteSpace(query))
            {
                var needle = query.Trim();
                identities = identities
                    .Where(identity => IdentityMatches(identity, needle))
                    .ToList();
            }

            return ToJson(identities
                .Take(Math.Clamp(limit, 1, 100))
                .Select(ToIdentitySummary)
                .ToList());
        }
    }

    public async Task<string> ReadIdentity(int identityId)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var identity = await LoadIdentities(context)
                .SingleOrDefaultAsync(identity => identity.Id == identityId);
            return identity is null
                ? $"Identity {identityId} was not found."
                : ToJson(ToIdentityDetail(identity));
        }
    }

    public async Task<string> CreateIdentity(
        string? canonicalName = null,
        string[]? aliases = null,
        string[]? candidateNames = null)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var now = DateTimeOffset.UtcNow;
            var identity = new SpeakerIdentity
            {
                CanonicalName = NormalizeNullable(canonicalName),
                CreatedAt = now,
                UpdatedAt = now,
                Aliases = NormalizeNames(aliases)
                    .Select(name => new SpeakerAlias { Name = name })
                    .ToList(),
                CandidateNames = NormalizeNames(candidateNames)
                    .Select(name => new SpeakerCandidateName { Name = name })
                    .ToList()
            };
            context.SpeakerIdentities.Add(identity);
            await context.SaveChangesAsync();
            return ToJson(ToIdentityDetail(identity));
        }
    }

    public async Task<string> UpdateIdentity(
        int identityId,
        string? canonicalName = null,
        string[]? aliases = null,
        string[]? candidateNames = null)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var identity = await LoadIdentities(context)
                .SingleOrDefaultAsync(identity => identity.Id == identityId);
            if (identity is null)
            {
                return $"Identity {identityId} was not found.";
            }

            identity.CanonicalName = NormalizeNullable(canonicalName);
            identity.Aliases.Clear();
            identity.Aliases.AddRange(NormalizeNames(aliases)
                .Select(name => new SpeakerAlias { Name = name }));
            identity.CandidateNames.Clear();
            identity.CandidateNames.AddRange(NormalizeNames(candidateNames)
                .Select(name => new SpeakerCandidateName { Name = name }));
            identity.UpdatedAt = DateTimeOffset.UtcNow;
            await context.SaveChangesAsync();
            return ToJson(ToIdentityDetail(identity));
        }
    }

    public async Task<string> DeleteIdentity(int identityId)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var identity = await LoadIdentities(context)
                .SingleOrDefaultAsync(identity => identity.Id == identityId);
            if (identity is null)
            {
                return $"Identity {identityId} was not found.";
            }

            context.SpeakerIdentities.Remove(identity);
            await context.SaveChangesAsync();
            return $"Deleted identity {identityId}.";
        }
    }

    public async Task<string> MergeIdentities(int targetIdentityId, int sourceIdentityId)
    {
        if (targetIdentityId == sourceIdentityId)
        {
            return "Refused: target and source identity are the same.";
        }

        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var target = await LoadIdentities(context).SingleOrDefaultAsync(identity => identity.Id == targetIdentityId);
            var source = await LoadIdentities(context).SingleOrDefaultAsync(identity => identity.Id == sourceIdentityId);
            if (target is null || source is null)
            {
                return $"Could not find target {targetIdentityId} or source {sourceIdentityId}.";
            }

            SpeakerIdentityMerger.MergeInto(
                target,
                source,
                speakerOptions.MaxSnippetsPerSpeaker);
            context.SpeakerIdentities.Remove(source);
            await context.SaveChangesAsync();
            return ToJson(ToIdentityDetail(target));
        }
    }

    public async Task<string> ListIdentitySamples(int identityId)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var samples = await context.SpeakerSnippets
                .Where(sample => sample.SpeakerIdentityId == identityId)
                .ToListAsync();
            return ToJson(samples
                .OrderBy(sample => sample.CreatedAt)
                .Select(ToIdentitySampleSummary)
                .ToList());
        }
    }

    public async Task<string> ReadIdentitySample(int sampleId)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var sample = await context.SpeakerSnippets.SingleOrDefaultAsync(sample => sample.Id == sampleId);
            return sample is null
                ? $"Sample {sampleId} was not found."
                : ToJson(new IdentitySampleDetail(
                    sample.Id,
                    sample.SpeakerIdentityId,
                    sample.CreatedAt,
                    sample.WavBytes.Length,
                    Convert.ToBase64String(sample.WavBytes)));
        }
    }

    public async Task<string> DeleteIdentitySample(int sampleId)
    {
        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var sample = await context.SpeakerSnippets.SingleOrDefaultAsync(sample => sample.Id == sampleId);
            if (sample is null)
            {
                return $"Sample {sampleId} was not found.";
            }

            context.SpeakerSnippets.Remove(sample);
            await context.SaveChangesAsync();
            return $"Deleted sample {sampleId}.";
        }
    }

    public async Task<string> QueuePlayIdentitySample(int sampleId)
    {
        if (samplePlaybackQueue is null)
        {
            return "Sample playback queue is not configured.";
        }

        var context = await CreatePreparedIdentityContextAsync(CancellationToken.None);
        if (context is null)
        {
            return "Speaker identity database is not configured.";
        }

        await using (context)
        {
            var sample = await context.SpeakerSnippets.SingleOrDefaultAsync(sample => sample.Id == sampleId);
            return sample is null
                ? $"Sample {sampleId} was not found."
                : await samplePlaybackQueue.QueueAsync(sample.Id, sample.WavBytes);
        }
    }

    private static string? ValidateYaml(string yaml)
    {
        if (string.IsNullOrWhiteSpace(yaml))
        {
            return null;
        }

        try
        {
            _ = YamlDeserializer.Deserialize<MeetingWorkflowRulesFile>(yaml);
            return null;
        }
        catch (YamlException exception)
        {
            return $"Refused: workflow rules YAML is invalid. {exception.Message}";
        }
    }

    private static async Task<string?> RunRipgrepAsync(string rulesPath, string keywords)
    {
        try
        {
            var startInfo = new ProcessStartInfo
            {
                FileName = "rg",
                WorkingDirectory = Path.GetDirectoryName(rulesPath)!,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false
            };
            startInfo.ArgumentList.Add("--json");
            startInfo.ArgumentList.Add("--line-number");
            startInfo.ArgumentList.Add("--color");
            startInfo.ArgumentList.Add("never");
            startInfo.ArgumentList.Add("--");
            startInfo.ArgumentList.Add(keywords);
            startInfo.ArgumentList.Add(Path.GetFileName(rulesPath));

            using var process = Process.Start(startInfo);
            if (process is null)
            {
                return null;
            }

            var output = await process.StandardOutput.ReadToEndAsync();
            await process.WaitForExitAsync();
            return process.ExitCode is 0 or 1 ? output : null;
        }
        catch
        {
            return null;
        }
    }

    private static string FormatRipgrepJson(string output)
    {
        var matches = new List<string>();
        using var reader = new StringReader(output);
        string? line;
        while ((line = reader.ReadLine()) is not null)
        {
            using var document = JsonDocument.Parse(line);
            var root = document.RootElement;
            if (!root.TryGetProperty("type", out var type) ||
                type.GetString() != "match" ||
                !root.TryGetProperty("data", out var data))
            {
                continue;
            }

            var path = data.GetProperty("path").GetProperty("text").GetString() ?? "";
            var lineNumber = data.GetProperty("line_number").GetInt32();
            var text = data.GetProperty("lines").GetProperty("text").GetString() ?? "";
            matches.Add($"{ToToolPath(path)}:{lineNumber} {text.TrimEnd('\r', '\n')}");
        }

        return string.Join('\n', matches);
    }

    private static string SearchWithRegexFallback(string rulesPath, string keywords)
    {
        try
        {
            var regex = new Regex(keywords, RegexOptions.IgnoreCase);
            var matches = new List<string>();
            var lines = File.ReadAllLines(rulesPath);
            for (var index = 0; index < lines.Length; index++)
            {
                if (regex.IsMatch(lines[index]))
                {
                    matches.Add($"{Path.GetFileName(rulesPath)}:{index + 1} {lines[index]}");
                }
            }

            return string.Join('\n', matches);
        }
        catch
        {
            return "";
        }
    }

    private static string ReadLines(string content, int? from = null, int? to = null)
    {
        if (!from.HasValue && !to.HasValue)
        {
            return content;
        }

        var lines = content
            .Replace("\r\n", "\n", StringComparison.Ordinal)
            .Replace('\r', '\n')
            .Split('\n')
            .ToList();
        if (lines.Count == 0)
        {
            return "";
        }

        var start = Math.Clamp((from ?? 1) - 1, 0, lines.Count - 1);
        var end = Math.Clamp((to ?? lines.Count) - 1, 0, lines.Count - 1);
        if (end < start)
        {
            return "";
        }

        return string.Join('\n', lines.GetRange(start, end - start + 1));
    }

    private static string ToToolPath(string path)
    {
        return path.Replace(Path.DirectorySeparatorChar.ToString(), "/", StringComparison.Ordinal)
            .Replace(Path.AltDirectorySeparatorChar.ToString(), "/", StringComparison.Ordinal);
    }

    private async Task<SpeakerIdentityDbContext?> CreateIdentityContextAsync(CancellationToken cancellationToken)
    {
        return dbContextFactory is null
            ? null
            : await dbContextFactory.CreateDbContextAsync(cancellationToken);
    }

    private async Task<SpeakerIdentityDbContext?> CreatePreparedIdentityContextAsync(CancellationToken cancellationToken)
    {
        var context = await CreateIdentityContextAsync(cancellationToken);
        if (context is null)
        {
            return null;
        }

        await SpeakerIdentitySchema.EnsureCreatedOrUpdatedAsync(context, cancellationToken);
        return context;
    }

    private static IQueryable<SpeakerIdentity> LoadIdentities(SpeakerIdentityDbContext context)
    {
        return context.SpeakerIdentities
            .Include(identity => identity.Aliases)
            .Include(identity => identity.CandidateNames)
            .Include(identity => identity.Snippets)
            .Include(identity => identity.References);
    }

    private static bool IdentityMatches(SpeakerIdentity identity, string query)
    {
        return new[] { identity.CanonicalName }
            .Concat(identity.Aliases.Select(alias => alias.Name))
            .Concat(identity.CandidateNames.Select(candidate => candidate.Name))
            .Where(value => !string.IsNullOrWhiteSpace(value))
            .Any(value => value!.Contains(query, StringComparison.OrdinalIgnoreCase));
    }

    private static IdentitySummary ToIdentitySummary(SpeakerIdentity identity)
    {
        return new IdentitySummary(
            identity.Id,
            identity.CanonicalName,
            identity.GetDisplayName(),
            identity.Aliases.Select(alias => alias.Name).Order(StringComparer.OrdinalIgnoreCase).ToArray(),
            identity.CandidateNames.Select(candidate => candidate.Name).Order(StringComparer.OrdinalIgnoreCase).ToArray(),
            identity.Snippets.Count,
            identity.References.Count,
            identity.UpdatedAt);
    }

    private static IdentityDetail ToIdentityDetail(SpeakerIdentity identity)
    {
        return new IdentityDetail(
            ToIdentitySummary(identity),
            identity.References
                .OrderByDescending(reference => reference.CreatedAt)
                .Select(reference => new IdentityReferenceDetail(
                    reference.Id,
                    reference.MeetingNotePath,
                    reference.TranscriptPath,
                    reference.CreatedAt))
                .ToArray(),
            identity.Snippets
                .OrderBy(sample => sample.CreatedAt)
                .Select(ToIdentitySampleSummary)
                .ToArray());
    }

    private static IdentitySampleSummary ToIdentitySampleSummary(SpeakerSnippet sample)
    {
        return new IdentitySampleSummary(
            sample.Id,
            sample.SpeakerIdentityId,
            sample.CreatedAt,
            sample.WavBytes.Length);
    }

    private static IReadOnlyList<string> NormalizeNames(IEnumerable<string>? names)
    {
        return names?
            .Select(name => name.Trim())
            .Where(name => !string.IsNullOrWhiteSpace(name))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .Order(StringComparer.OrdinalIgnoreCase)
            .ToArray()
            ?? [];
    }

    private static string? NormalizeNullable(string? value)
    {
        return string.IsNullOrWhiteSpace(value) ? null : value.Trim();
    }

    private static string ToJson<T>(T value)
    {
        return JsonSerializer.Serialize(value, JsonOptions);
    }

    private sealed record IdentitySummary(
        int Id,
        string? CanonicalName,
        string? DisplayName,
        IReadOnlyList<string> Aliases,
        IReadOnlyList<string> CandidateNames,
        int SampleCount,
        int ReferenceCount,
        DateTimeOffset UpdatedAt);

    private sealed record IdentityDetail(
        IdentitySummary Identity,
        IReadOnlyList<IdentityReferenceDetail> References,
        IReadOnlyList<IdentitySampleSummary> Samples);

    private sealed record IdentityReferenceDetail(
        int Id,
        string MeetingNotePath,
        string TranscriptPath,
        DateTimeOffset CreatedAt);

    private sealed record IdentitySampleSummary(
        int Id,
        int IdentityId,
        DateTimeOffset CreatedAt,
        int ByteCount);

    private sealed record IdentitySampleDetail(
        int Id,
        int IdentityId,
        DateTimeOffset CreatedAt,
        int ByteCount,
        string Base64Wav);
}