package appendorder

import (
	"context"
	"encoding/json"
	"reflect"
	"testing"

	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
)

func TestModuleSpecAndRegister(t *testing.T) {
	want := pipeline.ModuleSpec{
		Key:      Key,
		Stage:    pipeline.StageMerge,
		Provides: []string{"merged"},
	}
	if got := ModuleSpec(); !reflect.DeepEqual(got, want) {
		t.Fatalf("ModuleSpec() = %#v, want %#v", got, want)
	}

	registry := pipeline.NewMergerRegistry()
	if err := Register(registry); err != nil {
		t.Fatalf("Register() error = %v, want nil", err)
	}
	spec, ok := registry.Spec(Key)
	if !ok {
		t.Fatalf("Spec(%q) ok = false, want true", Key)
	}
	if !reflect.DeepEqual(spec, want) {
		t.Fatalf("registered spec = %#v, want %#v", spec, want)
	}
}

func TestMergePreservesChunkAndCandidateOrder(t *testing.T) {
	result, err := New().Merge(context.Background(), contracts.MergeRequest{
		ChunkArtifacts: []contracts.ChunkArtifacts{
			{
				Chunk:      sourceChunk(0),
				Candidates: []artifacts.ArtifactCandidate{candidate(2, "first-b"), candidate(1, "first-a")},
			},
			{
				Chunk:      sourceChunk(1),
				Candidates: []artifacts.ArtifactCandidate{candidate(4, "second-b"), candidate(3, "second-a")},
			},
		},
	})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}

	got := candidateNames(result.Candidates)
	want := []string{"first-b", "first-a", "second-b", "second-a"}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("candidate order = %#v, want %#v", got, want)
	}
	if len(result.Warnings) != 0 {
		t.Fatalf("Warnings = %#v, want none", result.Warnings)
	}
}

func TestMergeDefensivelyCopiesCandidates(t *testing.T) {
	input := []contracts.ChunkArtifacts{
		{
			Chunk:      sourceChunk(0),
			Candidates: []artifacts.ArtifactCandidate{candidate(1, "original")},
		},
	}

	result, err := New().Merge(context.Background(), contracts.MergeRequest{ChunkArtifacts: input})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}
	if len(result.Candidates) != 1 {
		t.Fatalf("len(Candidates) = %d, want 1", len(result.Candidates))
	}

	input[0].Candidates[0].Index = 99
	input[0].Candidates[0].Payload[0] = '['
	input[0].Candidates[0].SourceRefs[0].StartUnitID = "changed"
	input[0].Candidates[0].Metadata["name"] = "changed"

	got := result.Candidates[0]
	if got.Index != 1 {
		t.Fatalf("Index = %d, want 1", got.Index)
	}
	if string(got.Payload) != `{"name":"original"}` {
		t.Fatalf("Payload = %s, want original payload", got.Payload)
	}
	if got.SourceRefs[0].StartUnitID != "u1" {
		t.Fatalf("SourceRefs = %#v, want original source ref", got.SourceRefs)
	}
	if got.Metadata["name"] != "original" {
		t.Fatalf("Metadata = %#v, want original metadata", got.Metadata)
	}
}

func TestMergeHandlesEmptyInput(t *testing.T) {
	result, err := New().Merge(context.Background(), contracts.MergeRequest{})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}
	if len(result.Candidates) != 0 {
		t.Fatalf("len(Candidates) = %d, want 0", len(result.Candidates))
	}
	if len(result.Warnings) != 0 {
		t.Fatalf("Warnings = %#v, want none", result.Warnings)
	}
}

func candidate(index int, name string) artifacts.ArtifactCandidate {
	return artifacts.ArtifactCandidate{
		Index:         index,
		ExtractorKey:  "generic-extractor",
		ArtifactType:  "generic-artifact",
		SchemaVersion: "v1",
		Payload:       json.RawMessage(`{"name":"` + name + `"}`),
		SourceRefs: []source.SourceRef{
			{SourceID: "source-1", StartUnitID: "u1", EndUnitID: "u1"},
		},
		Metadata: map[string]any{
			"name": name,
		},
	}
}

func candidateNames(candidates []artifacts.ArtifactCandidate) []string {
	names := make([]string, 0, len(candidates))
	for _, candidate := range candidates {
		names = append(names, candidate.Metadata["name"].(string))
	}
	return names
}

func sourceChunk(index int) contracts.SourceChunk {
	return contracts.SourceChunk{
		ID:       "chunk",
		SourceID: "source-1",
		Index:    index,
		Units: []source.SourceUnit{
			{ID: "u1", Kind: "unit", Text: "Source unit."},
		},
	}
}