using MeetingAssistant.MeetingNotes;

namespace MeetingAssistant.Speakers;

internal static class SpeakerIdentityNaming
{
    public static IReadOnlySet<string> GetAcceptedNames(SpeakerIdentity identity)
    {
        return new[] { identity.CanonicalName }
            .Concat(identity.Aliases.Select(alias => alias.Name))
            .Concat(identity.CandidateNames.Select(candidate => candidate.Name))
            .Where(name => !string.IsNullOrWhiteSpace(name))
            .Select(name => name!.Trim())
            .ToHashSet(StringComparer.OrdinalIgnoreCase);
    }

    public static bool MatchesAnyAcceptedName(
        SpeakerIdentity identity,
        IReadOnlySet<string> names)
    {
        return GetAcceptedNames(identity).Any(names.Contains);
    }

    public static bool MatchesAttendees(
        SpeakerIdentity identity,
        IReadOnlyList<string> attendees)
    {
        var attendeeSet = attendees.ToHashSet(StringComparer.OrdinalIgnoreCase);
        return GetAcceptedNames(identity).Any(attendeeSet.Contains);
    }

    public static IReadOnlyList<string> NormalizeAttendees(IEnumerable<string> attendees)
    {
        return attendees
            .Select(MeetingAttendeeNames.NormalizeDisplayName)
            .Where(attendee => !string.IsNullOrWhiteSpace(attendee))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .Order(StringComparer.OrdinalIgnoreCase)
            .ToList();
    }

    public static bool IsDiarizedSpeakerLabel(string speaker)
    {
        var normalized = speaker.Trim();
        return normalized.Equals("Unknown", StringComparison.OrdinalIgnoreCase) ||
            normalized.StartsWith("Guest", StringComparison.OrdinalIgnoreCase) ||
            normalized.StartsWith("Speaker", StringComparison.OrdinalIgnoreCase);
    }

    public static bool UpdateCandidateNames(
        SpeakerIdentity identity,
        IReadOnlyList<string> attendees)
    {
        if (!string.IsNullOrWhiteSpace(identity.CanonicalName) || attendees.Count == 0)
        {
            return false;
        }

        var currentCandidates = identity.CandidateNames
            .Select(candidate => candidate.Name)
            .ToHashSet(StringComparer.OrdinalIgnoreCase);
        var fallbackAliasCandidate = currentCandidates.Count == 1 ? currentCandidates.Single() : null;
        var aliasToCandidate = identity.Aliases
            .Where(alias => !string.IsNullOrWhiteSpace(alias.Name))
            .SelectMany(alias => currentCandidates.Select(candidate => new { Alias = alias.Name, Candidate = candidate }))
            .Where(pair => string.Equals(pair.Alias, pair.Candidate, StringComparison.OrdinalIgnoreCase) ||
                pair.Alias.Contains(pair.Candidate, StringComparison.OrdinalIgnoreCase) ||
                pair.Candidate.Contains(pair.Alias, StringComparison.OrdinalIgnoreCase))
            .ToDictionary(pair => pair.Alias, pair => pair.Candidate, StringComparer.OrdinalIgnoreCase);
        var intersection = attendees
            .Select(attendee => currentCandidates.Contains(attendee)
                ? attendee
                : aliasToCandidate.GetValueOrDefault(attendee) ??
                    (identity.Aliases.Any(alias => string.Equals(alias.Name, attendee, StringComparison.OrdinalIgnoreCase))
                        ? fallbackAliasCandidate
                        : null))
            .Where(candidate => !string.IsNullOrWhiteSpace(candidate))
            .Select(candidate => candidate!)
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .Order(StringComparer.OrdinalIgnoreCase)
            .ToList();
        var resetToAttendees = intersection.Count == 0;
        SetCandidates(identity, resetToAttendees ? attendees : intersection);
        if (intersection.Count == 1)
        {
            identity.CanonicalName = intersection[0];
        }

        return resetToAttendees;
    }

    public static void SetCandidates(
        SpeakerIdentity identity,
        IEnumerable<string> candidates)
    {
        identity.CandidateNames.Clear();
        identity.CandidateNames.AddRange(candidates
            .Where(candidate => !string.IsNullOrWhiteSpace(candidate))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .Order(StringComparer.OrdinalIgnoreCase)
            .Select(candidate => new SpeakerCandidateName { Name = candidate }));
    }
}