using Microsoft.EntityFrameworkCore;
using NovelSoftware.Application.Dtos;
using NovelSoftware.Domain.Entities;

namespace NovelSoftware.Application.Services;

public class CharacterService(INovelDbContext db)
{
    public async Task<IReadOnlyList<CharacterDto>> ListAsync(Guid projectId, CancellationToken ct = default)
    {
        var characters = await Query()
            .Where(c => c.ProjectId == projectId)
            .OrderBy(c => c.Role)
            .ThenBy(c => c.Name)
            .ToListAsync(ct);

        return [.. characters.Select(c => c.ToDto())];
    }

    public async Task<CharacterDto> GetAsync(Guid id, CancellationToken ct = default) =>
        (await FindAsync(id, ct)).ToDto();

    public async Task<CharacterDto> CreateAsync(Guid projectId, CreateCharacterRequest request, CancellationToken ct = default)
    {
        await EnsureProjectExists(projectId, ct);

        var character = new Character
        {
            ProjectId = projectId,
            Name = request.Name,
            Role = request.Role,
            Age = request.Age,
            Pronouns = request.Pronouns,
            Occupation = request.Occupation,
            Appearance = request.Appearance,
            Personality = request.Personality,
            Backstory = request.Backstory,
            Want = request.Want,
            Need = request.Need,
            InternalConflict = request.InternalConflict,
            ExternalConflict = request.ExternalConflict,
            ArcSummary = request.ArcSummary,
            Voice = request.Voice,
            Notes = request.Notes
        };

        db.Characters.Add(character);
        await db.SaveChangesAsync(ct);
        return character.ToDto();
    }

    public async Task<CharacterDto> UpdateAsync(Guid id, UpdateCharacterRequest request, CancellationToken ct = default)
    {
        var character = await FindAsync(id, ct);

        character.Name = Patch.Apply(character.Name, request.Name) ?? character.Name;
        character.Role = request.Role ?? character.Role;
        character.Age = Patch.Apply(character.Age, request.Age);
        character.Pronouns = Patch.Apply(character.Pronouns, request.Pronouns);
        character.Occupation = Patch.Apply(character.Occupation, request.Occupation);
        character.Appearance = Patch.Apply(character.Appearance, request.Appearance);
        character.Personality = Patch.Apply(character.Personality, request.Personality);
        character.Backstory = Patch.Apply(character.Backstory, request.Backstory);
        character.Want = Patch.Apply(character.Want, request.Want);
        character.Need = Patch.Apply(character.Need, request.Need);
        character.InternalConflict = Patch.Apply(character.InternalConflict, request.InternalConflict);
        character.ExternalConflict = Patch.Apply(character.ExternalConflict, request.ExternalConflict);
        character.ArcSummary = Patch.Apply(character.ArcSummary, request.ArcSummary);
        character.Voice = Patch.Apply(character.Voice, request.Voice);
        character.Notes = Patch.Apply(character.Notes, request.Notes);
        character.UpdatedAt = DateTimeOffset.UtcNow;

        await db.SaveChangesAsync(ct);
        return character.ToDto();
    }

    public async Task DeleteAsync(Guid id, CancellationToken ct = default)
    {
        var character = await FindAsync(id, ct);
        db.Characters.Remove(character);
        await db.SaveChangesAsync(ct);
    }

    public async Task<CharacterDto> AddRelationshipAsync(
        Guid characterId, CreateRelationshipRequest request, CancellationToken ct = default)
    {
        var character = await FindAsync(characterId, ct);

        var related = await db.Characters
            .FirstOrDefaultAsync(c => c.Id == request.RelatedCharacterId, ct)
            ?? throw new NotFoundException(nameof(Character), request.RelatedCharacterId);

        if (related.ProjectId != character.ProjectId)
        {
            throw new InvalidOperationException("Characters must belong to the same project to be related.");
        }

        db.CharacterRelationships.Add(new CharacterRelationship
        {
            CharacterId = characterId,
            RelatedCharacterId = request.RelatedCharacterId,
            RelationshipType = request.RelationshipType,
            Description = request.Description
        });

        await db.SaveChangesAsync(ct);
        return (await FindAsync(characterId, ct)).ToDto();
    }

    public async Task RemoveRelationshipAsync(Guid relationshipId, CancellationToken ct = default)
    {
        var relationship = await db.CharacterRelationships
            .FirstOrDefaultAsync(r => r.Id == relationshipId, ct)
            ?? throw new NotFoundException(nameof(CharacterRelationship), relationshipId);

        db.CharacterRelationships.Remove(relationship);
        await db.SaveChangesAsync(ct);
    }

    private IQueryable<Character> Query() =>
        db.Characters
            .Include(c => c.Relationships)
            .ThenInclude(r => r.RelatedCharacter);

    private async Task<Character> FindAsync(Guid id, CancellationToken ct) =>
        await Query().FirstOrDefaultAsync(c => c.Id == id, ct)
        ?? throw new NotFoundException(nameof(Character), id);

    private async Task EnsureProjectExists(Guid projectId, CancellationToken ct)
    {
        if (!await db.Projects.AnyAsync(p => p.Id == projectId, ct))
        {
            throw new NotFoundException(nameof(Project), projectId);
        }
    }
}