package appendorder

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

	"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 TestMergePassesThroughSingleExtractOutput(t *testing.T) {
	input := extractOutput("chunk-0", 0, `{"name":"original"}`)

	result, err := New().Merge(context.Background(), contracts.MergeRequest{
		LaneID:         "events",
		ExtractOutputs: []contracts.ExtractOutput{input},
	})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}

	if result.Output.LaneID != "events" || result.Output.MergerKey != Key {
		t.Fatalf("output provenance = %#v, want lane and merger", result.Output)
	}
	if string(result.Output.Payload.Content) != `{"name":"original"}` {
		t.Fatalf("content = %s, want original content", result.Output.Payload.Content)
	}
	if result.Output.Payload.Metadata["name"] != "chunk-0" {
		t.Fatalf("metadata = %#v, want original metadata", result.Output.Payload.Metadata)
	}
}

func TestMergeDefensivelyCopiesRawPayload(t *testing.T) {
	input := extractOutput("chunk-0", 0, `{"name":"original"}`)

	result, err := New().Merge(context.Background(), contracts.MergeRequest{
		LaneID:         "events",
		ExtractOutputs: []contracts.ExtractOutput{input},
	})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}

	input.Payload.Content[0] = '['
	input.Payload.Metadata["name"] = "changed"

	if string(result.Output.Payload.Content) != `{"name":"original"}` {
		t.Fatalf("content changed after input mutation: %s", result.Output.Payload.Content)
	}
	if result.Output.Payload.Metadata["name"] != "chunk-0" {
		t.Fatalf("metadata changed after input mutation: %#v", result.Output.Payload.Metadata)
	}
}

func TestMergeConcatenatesCommonTopLevelArrayFieldInChunkOrder(t *testing.T) {
	result, err := New().Merge(context.Background(), contracts.MergeRequest{
		LaneID: "events",
		ExtractOutputs: []contracts.ExtractOutput{
			extractOutput("chunk-1", 1, `{"events":[{"name":"second"}]}`),
			extractOutput("chunk-0", 0, `{"events":[{"name":"first"}]}`),
		},
	})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}
	if result.Output.Payload.MediaType != "application/json" {
		t.Fatalf("MediaType = %q, want application/json", result.Output.Payload.MediaType)
	}

	var decoded struct {
		Events []struct {
			Name string `json:"name"`
		} `json:"events"`
	}
	if err := json.Unmarshal(result.Output.Payload.Content, &decoded); err != nil {
		t.Fatalf("Unmarshal() error = %v, want nil", err)
	}
	if len(decoded.Events) != 2 || decoded.Events[0].Name != "first" || decoded.Events[1].Name != "second" {
		t.Fatalf("events = %#v, want concatenated chunk order", decoded.Events)
	}
	if result.Output.Schema.ID != "schema-id" {
		t.Fatalf("schema = %#v, want common extract schema", result.Output.Schema)
	}
}

func TestMergeFallsBackToOrderedJSONValueArrayWhenShapesDiffer(t *testing.T) {
	result, err := New().Merge(context.Background(), contracts.MergeRequest{
		LaneID: "events",
		ExtractOutputs: []contracts.ExtractOutput{
			extractOutput("chunk-1", 1, `{"notes":["second"]}`),
			extractOutput("chunk-0", 0, `{"events":[{"name":"first"}]}`),
		},
	})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}

	var decoded []map[string]any
	if err := json.Unmarshal(result.Output.Payload.Content, &decoded); err != nil {
		t.Fatalf("Unmarshal() error = %v, want nil", err)
	}
	if len(decoded) != 2 {
		t.Fatalf("len(decoded) = %d, want 2", len(decoded))
	}
	if _, ok := decoded[0]["events"]; !ok {
		t.Fatalf("decoded[0] = %#v, want first chunk value", decoded[0])
	}
	if _, ok := decoded[1]["notes"]; !ok {
		t.Fatalf("decoded[1] = %#v, want second chunk value", decoded[1])
	}
}

func TestMergeRejectsInvalidJSONAndNonJSONMediaTypes(t *testing.T) {
	tests := []struct {
		name   string
		output contracts.ExtractOutput
		want   string
	}{
		{
			name:   "invalid JSON",
			output: extractOutput("chunk-0", 0, `{"events":[`),
			want:   "invalid JSON",
		},
		{
			name: "non JSON media type",
			output: func() contracts.ExtractOutput {
				output := extractOutput("chunk-0", 0, `{"events":[]}`)
				output.Payload.MediaType = "text/plain"
				return output
			}(),
			want: "unsupported media type",
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			_, err := New().Merge(context.Background(), contracts.MergeRequest{
				LaneID:         "events",
				ExtractOutputs: []contracts.ExtractOutput{test.output},
			})
			if err == nil {
				t.Fatal("Merge() error = nil, want error")
			}
			if !strings.Contains(err.Error(), test.want) {
				t.Fatalf("Merge() error = %q, want %q", err.Error(), test.want)
			}
		})
	}
}

func extractOutput(chunkID string, chunkIndex int, content string) contracts.ExtractOutput {
	return contracts.ExtractOutput{
		LaneID:       "events",
		ExtractorKey: "extract",
		SourceID:     "source-1",
		ChunkID:      chunkID,
		ChunkIndex:   chunkIndex,
		Schema:       contracts.ResponseSchema{ID: "schema-id", Name: "schema-name", Version: "v1"},
		Payload: contracts.RawPayload{
			Content:   []byte(content),
			MediaType: "application/json",
			Metadata:  map[string]any{"name": chunkID},
		},
	}
}