using backend.Data;
using Microsoft.EntityFrameworkCore;

namespace backend.Conversations;

public class ConversationLog(AppDbContext db)
{
    public async Task<Conversation> StartAsync(Guid deviceId, CancellationToken ct)
    {
        var c = new Conversation
        {
            DeviceId = deviceId,
            StartedAt = DateTimeOffset.UtcNow,
        };
        db.Conversations.Add(c);
        await db.SaveChangesAsync(ct);
        return c;
    }

    public Task AppendUserAsync(Guid conversationId, string text, CancellationToken ct)
        => AppendAsync(conversationId, TurnRole.User, text: text, ct: ct);

    public Task AppendAssistantAsync(Guid conversationId, string text, CancellationToken ct)
        => AppendAsync(conversationId, TurnRole.Assistant, text: text, ct: ct);

    public Task AppendToolAsync(
        Guid conversationId, string toolName, string argsJson, string resultJson, CancellationToken ct)
        => AppendAsync(conversationId, TurnRole.Tool,
            toolName: toolName, argsJson: argsJson, resultJson: resultJson, ct: ct);

    public async Task EndAsync(Guid conversationId, EndReason reason, CancellationToken ct)
    {
        var row = await db.Conversations.FirstAsync(c => c.Id == conversationId, ct);
        row.EndedAt = DateTimeOffset.UtcNow;
        row.EndReason = reason;
        await db.SaveChangesAsync(ct);
    }

    private async Task AppendAsync(
        Guid conversationId, TurnRole role,
        string? text = null, string? toolName = null,
        string? argsJson = null, string? resultJson = null,
        CancellationToken ct = default)
    {
        var next = await db.Turns
            .Where(t => t.ConversationId == conversationId)
            .Select(t => (int?)t.Index)
            .MaxAsync(ct) ?? -1;

        db.Turns.Add(new Turn
        {
            ConversationId = conversationId,
            Index = next + 1,
            Role = role,
            Text = text,
            ToolName = toolName,
            ToolArgsJson = argsJson,
            ToolResultJson = resultJson,
            CreatedAt = DateTimeOffset.UtcNow,
        });
        await db.SaveChangesAsync(ct);
    }
}