using MeetingAssistant.MeetingNotes;
using Microsoft.Extensions.Options;

namespace MeetingAssistant.Summary;

public interface IMeetingSummaryArtifactResolver
{
    Task<MeetingSessionArtifacts?> ResolveBySummaryPathAsync(
        string summaryPath,
        CancellationToken cancellationToken);

    Task<MeetingSessionArtifacts?> ResolveBySummaryPathAsync(
        string summaryPath,
        MeetingAssistantOptions options,
        CancellationToken cancellationToken)
    {
        return ResolveBySummaryPathAsync(summaryPath, cancellationToken);
    }
}

public sealed class MeetingSummaryArtifactResolver : IMeetingSummaryArtifactResolver
{
    private readonly MeetingAssistantOptions options;
    private readonly IMeetingNoteStore meetingNoteStore;

    public MeetingSummaryArtifactResolver(
        IOptions<MeetingAssistantOptions> options,
        IMeetingNoteStore meetingNoteStore)
    {
        this.options = options.Value;
        this.meetingNoteStore = meetingNoteStore;
    }

    public async Task<MeetingSessionArtifacts?> ResolveBySummaryPathAsync(
        string summaryPath,
        CancellationToken cancellationToken)
    {
        return await ResolveBySummaryPathAsync(summaryPath, options, cancellationToken);
    }

    public async Task<MeetingSessionArtifacts?> ResolveBySummaryPathAsync(
        string summaryPath,
        MeetingAssistantOptions options,
        CancellationToken cancellationToken)
    {
        var requestedSummaryPath = ResolveRequestedSummaryPath(summaryPath, options);
        if (requestedSummaryPath is null)
        {
            return null;
        }

        var meetingNotesFolder = VaultPath.Resolve(options.Vault, options.Vault.MeetingNotesFolder);
        if (!Directory.Exists(meetingNotesFolder))
        {
            return null;
        }

        foreach (var meetingNotePath in Directory.EnumerateFiles(meetingNotesFolder, "*.md"))
        {
            var note = await meetingNoteStore.ReadAsync(meetingNotePath, cancellationToken);
            var noteSummaryPath = ResolveNoteLink(note.Frontmatter.Summary, note.Path);
            if (!PathsEqual(requestedSummaryPath, noteSummaryPath))
            {
                continue;
            }

            return new MeetingSessionArtifacts(
                note.Path,
                ResolveNoteLink(note.Frontmatter.Transcript, note.Path),
                ResolveNoteLink(note.Frontmatter.AssistantContext, note.Path),
                requestedSummaryPath);
        }

        return null;
    }

    private static string? ResolveRequestedSummaryPath(
        string summaryPath,
        MeetingAssistantOptions options)
    {
        if (string.IsNullOrWhiteSpace(summaryPath))
        {
            return null;
        }

        var summariesFolder = VaultPath.Resolve(options.Vault, options.Vault.SummariesFolder);
        var requested = Environment.ExpandEnvironmentVariables(summaryPath);
        var fullPath = Path.IsPathRooted(requested)
            ? Path.GetFullPath(requested)
            : Path.GetFullPath(Path.Combine(summariesFolder, requested));

        return IsWithinDirectory(summariesFolder, fullPath) ? fullPath : null;
    }

    private static string ResolveNoteLink(string pathOrLink, string sourceNotePath)
    {
        if (string.IsNullOrWhiteSpace(pathOrLink))
        {
            return "";
        }

        var sourceFolder = Path.GetDirectoryName(sourceNotePath) ?? "";
        var target = ExtractWikiLinkTarget(pathOrLink) ?? pathOrLink;
        target = target.Replace('/', Path.DirectorySeparatorChar);

        if (!Path.HasExtension(target))
        {
            target += ".md";
        }

        return Path.GetFullPath(Path.IsPathRooted(target)
            ? target
            : Path.Combine(sourceFolder, target));
    }

    private static string? ExtractWikiLinkTarget(string value)
    {
        if (!value.StartsWith("[[", StringComparison.Ordinal) ||
            !value.EndsWith("]]", StringComparison.Ordinal))
        {
            return null;
        }

        var inner = value[2..^2];
        var labelSeparator = inner.IndexOf('|', StringComparison.Ordinal);
        return labelSeparator < 0 ? inner : inner[..labelSeparator];
    }

    private static bool PathsEqual(string left, string right)
    {
        return string.Equals(
            Path.GetFullPath(left),
            Path.GetFullPath(right),
            StringComparison.OrdinalIgnoreCase);
    }

    private static bool IsWithinDirectory(string directory, string path)
    {
        var normalizedDirectory = Path.GetFullPath(directory)
            .TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar) + Path.DirectorySeparatorChar;
        var normalizedPath = Path.GetFullPath(path);
        return normalizedPath.StartsWith(normalizedDirectory, StringComparison.OrdinalIgnoreCase);
    }
}