using System.Security.Cryptography;
using System.Text;
using Microsoft.EntityFrameworkCore;
using Pgvector;
using TeamUp.Modules.Skills.Domain;
using TeamUp.Modules.Skills.Parsing;
using TeamUp.Modules.Skills.Persistence;

namespace TeamUp.Modules.Skills.Indexing;

/// <summary>Parses a SKILL.md, computes its embedding, and upserts the Skill row (by key+version).</summary>
internal sealed class SkillIndexer(SkillsDbContext db, ISkillEmbedder embedder, TimeProvider clock)
{
    public async Task<Skill> IndexAsync(
        string content,
        string? sourceRepo,
        string? sourcePath,
        string? sourceCommit,
        CancellationToken cancellationToken = default)
    {
        var parsed = SkillMarkdownParser.Parse(content);
        var manifest = parsed.Manifest;
        var now = clock.GetUtcNow();
        var contentHash = Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(content)));

        var embeddingText = $"{manifest.Name}\n{manifest.Summary}\n{string.Join(' ', manifest.Roles)}\n{parsed.Body}";
        var embedding = new Vector(embedder.Embed(embeddingText));

        // M2 publish gate (structural): a skill is published only if it declares roles and carries
        // at least one well-formed golden test. Executing the golden tests against a model — and
        // gating on edit distance — lands in M4 when the assembler/runtime exists.
        var status = manifest.Roles.Count > 0 && manifest.GoldenTests.Count > 0
            ? SkillStatus.Published
            : SkillStatus.Draft;

        var skill = await db.Skills
            .FirstOrDefaultAsync(s => s.SkillKey == manifest.Id && s.Version == manifest.Version, cancellationToken);

        var isNew = skill is null;
        skill ??= Skill.Create(manifest.Id, manifest.Version, now);
        skill.Index(manifest, parsed.Body, contentHash, sourceRepo, sourcePath, sourceCommit, embedding, status, now);

        if (isNew)
        {
            db.Skills.Add(skill);
        }

        await db.SaveChangesAsync(cancellationToken);
        return skill;
    }
}