package contracts_test

import (
	"context"
	"encoding/json"
	"errors"
	"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"
)

var _ contracts.InputAdapter = compositionAdapter{}
var _ contracts.Chunker = compositionChunker{}
var _ contracts.Extractor = compositionExtractor{}
var _ contracts.Merger = compositionMerger{}
var _ contracts.Normalizer = compositionNormalizer{}
var _ contracts.Validator = compositionValidator{}
var _ contracts.StructuredLLMClient = compositionLLMClient{}
var _ contracts.OutputEncoder = compositionOutputEncoder{}

func TestContractsComposeAcrossPackages(t *testing.T) {
	ctx := context.Background()
	adapter := compositionAdapter{}
	chunker := compositionChunker{}
	extractor := compositionExtractor{}
	merger := compositionMerger{}
	normalizer := compositionNormalizer{}
	encoder := compositionOutputEncoder{}

	doc, err := adapter.Parse(ctx, contracts.ParseRequest{SourceID: "source-1"})
	if err != nil {
		t.Fatalf("Parse() error = %v, want nil", err)
	}
	if err := source.ValidateDocument(doc); err != nil {
		t.Fatalf("ValidateDocument() error = %v, want nil", err)
	}

	chunking, err := chunker.Chunk(ctx, contracts.ChunkRequest{
		Source:    doc,
		LLMClient: compositionLLMClient{},
		Metadata:  map[string]any{"max_units": 2},
	})
	if err != nil {
		t.Fatalf("Chunk() error = %v, want nil", err)
	}
	if len(chunking.Chunks) != 1 {
		t.Fatalf("len(Chunks) = %d, want 1", len(chunking.Chunks))
	}

	extraction, err := extractor.Extract(ctx, contracts.ExtractionRequest{
		Source:         doc,
		Chunk:          &chunking.Chunks[0],
		AmbientContext: map[string]any{"synopsis": "example synopsis"},
	})
	if err != nil {
		t.Fatalf("Extract() error = %v, want nil", err)
	}
	if extraction.Output.Payload.MediaType != "application/json" {
		t.Fatalf("extract media type = %q, want application/json", extraction.Output.Payload.MediaType)
	}

	merge, err := merger.Merge(ctx, contracts.MergeRequest{
		Source:         doc,
		LaneID:         "generic-lane",
		ExtractOutputs: []contracts.ExtractOutput{extraction.Output},
	})
	if err != nil {
		t.Fatalf("Merge() error = %v, want nil", err)
	}
	if string(merge.Output.Payload.Content) != `{"value":"example"}` {
		t.Fatalf("merge output = %s, want extract payload", merge.Output.Payload.Content)
	}

	normalize, err := normalizer.Normalize(ctx, contracts.NormalizeRequest{
		Source:      doc,
		LaneID:      "generic-lane",
		MergeOutput: merge.Output,
	})
	if err != nil {
		t.Fatalf("Normalize() error = %v, want nil", err)
	}
	if string(normalize.Output.Payload.Content) != `{"value":"example"}` {
		t.Fatalf("normalize output = %s, want merge payload", normalize.Output.Payload.Content)
	}

	output, err := encoder.Encode(ctx, contracts.OutputRequest{
		Manifest:         artifacts.RunManifest{RunID: "run-1"},
		NormalizeOutputs: []contracts.NormalizeOutput{normalize.Output},
	})
	if err != nil {
		t.Fatalf("Encode() error = %v, want nil", err)
	}
	if len(output.Files) != 1 {
		t.Fatalf("len(Files) = %d, want 1", len(output.Files))
	}
	if output.Files[0].ContentType != "application/json" {
		t.Fatalf("ContentType = %q, want application/json", output.Files[0].ContentType)
	}
	if len(output.Files[0].Bytes) == 0 {
		t.Fatal("len(Bytes) = 0, want encoded bytes")
	}
}

type compositionAdapter struct{}

func (adapter compositionAdapter) Key() string {
	return "generic-input"
}

func (adapter compositionAdapter) Parse(ctx context.Context, req contracts.ParseRequest) (*source.SourceDocument, error) {
	return &source.SourceDocument{
		ID:     req.SourceID,
		Kind:   "document",
		Format: "text/plain",
		Digest: "sha256:abc123",
		Units: []source.SourceUnit{
			{ID: 1, Kind: "unit", Text: "First source unit."},
			{ID: 2, Kind: "unit", Text: "Second source unit."},
		},
	}, nil
}

type compositionChunker struct{}

func (chunker compositionChunker) Key() string {
	return "generic-chunker"
}

func (chunker compositionChunker) ReferenceSlots() []contracts.ReferenceSlot {
	return nil
}

func (chunker compositionChunker) Chunk(ctx context.Context, req contracts.ChunkRequest) (contracts.ChunkResult, error) {
	if req.Source == nil {
		return contracts.ChunkResult{}, errors.New("source document is required")
	}
	if req.LLMClient == nil {
		return contracts.ChunkResult{}, errors.New("structured llm client is required")
	}

	return contracts.ChunkResult{
		Chunks: []contracts.SourceChunk{
			{
				ID:          req.Source.ID + ":chunk:0",
				SourceID:    req.Source.ID,
				Index:       0,
				StartUnitID: req.Source.Units[0].ID,
				EndUnitID:   req.Source.Units[len(req.Source.Units)-1].ID,
				Content:     []byte(`{"units":[{"id":1,"kind":"unit","text":"First source unit."},{"id":2,"kind":"unit","text":"Second source unit."}]}`),
				MediaType:   "application/json",
				Units:       append([]source.SourceUnit(nil), req.Source.Units...),
				Metadata:    map[string]any{"strategy": "whole-document"},
			},
		},
	}, nil
}

type compositionLLMClient struct{}

func (client compositionLLMClient) CompleteStructured(ctx context.Context, req contracts.StructuredCompletionRequest, out any) (contracts.StructuredCompletionResponse, error) {
	return contracts.StructuredCompletionResponse{}, nil
}

type compositionExtractor struct{}

func (extractor compositionExtractor) Key() string {
	return "generic-extractor"
}

func (extractor compositionExtractor) ReferenceSlots() []contracts.ReferenceSlot {
	return nil
}

func (extractor compositionExtractor) Extract(ctx context.Context, req contracts.ExtractionRequest) (contracts.ExtractionResult, error) {
	if req.Source == nil {
		return contracts.ExtractionResult{}, errors.New("source document is required")
	}
	if req.AmbientContext["synopsis"] == "" {
		return contracts.ExtractionResult{}, errors.New("ambient synopsis is required")
	}

	return contracts.ExtractionResult{
		Output: contracts.ExtractOutput{
			Schema: contracts.ResponseSchema{ID: "schema-id", Name: "schema-name", Version: "v1"},
			Payload: contracts.RawPayload{
				Content:   []byte(`{"value":"example"}`),
				MediaType: "application/json",
			},
		},
	}, nil
}

type compositionMerger struct{}

func (merger compositionMerger) Key() string {
	return "generic-merger"
}

func (merger compositionMerger) Merge(ctx context.Context, req contracts.MergeRequest) (contracts.MergeResult, error) {
	output := req.ExtractOutputs[0]
	return contracts.MergeResult{Output: contracts.MergeOutput{
		LaneID:    req.LaneID,
		MergerKey: merger.Key(),
		SourceID:  output.SourceID,
		Schema:    output.Schema,
		Payload:   cloneCompositionPayload(output.Payload),
	}}, nil
}

type compositionNormalizer struct{}

func (normalizer compositionNormalizer) Key() string {
	return "generic-normalizer"
}

func (normalizer compositionNormalizer) ReferenceSlots() []contracts.ReferenceSlot {
	return nil
}

func (normalizer compositionNormalizer) Normalize(ctx context.Context, req contracts.NormalizeRequest) (contracts.NormalizeResult, error) {
	return contracts.NormalizeResult{Output: contracts.NormalizeOutput{
		LaneID:        req.LaneID,
		NormalizerKey: normalizer.Key(),
		SourceID:      req.MergeOutput.SourceID,
		Schema:        req.MergeOutput.Schema,
		Payload:       cloneCompositionPayload(req.MergeOutput.Payload),
	}}, nil
}

func cloneCompositionPayload(payload contracts.RawPayload) contracts.RawPayload {
	return contracts.RawPayload{
		Content:   append([]byte(nil), payload.Content...),
		MediaType: payload.MediaType,
		Metadata:  cloneCompositionMetadata(payload.Metadata),
		Warnings:  append([]contracts.Warning(nil), payload.Warnings...),
	}
}

func cloneCompositionMetadata(metadata map[string]any) map[string]any {
	if len(metadata) == 0 {
		return nil
	}
	out := make(map[string]any, len(metadata))
	for key, value := range metadata {
		out[key] = value
	}
	return out
}

type compositionValidator struct{}

func (validator compositionValidator) Name() string {
	return "generic-validator"
}

func (validator compositionValidator) ExecutionClass() contracts.ExecutionClass {
	return contracts.ExecutionClassDeterministic
}

func (validator compositionValidator) Validate(ctx context.Context, req contracts.ValidationRequest) (contracts.ValidationResult, error) {
	return contracts.ValidationResult{
		Approved:   true,
		ReasonCode: "accepted",
		Message:    "output accepted",
	}, nil
}

type compositionOutputEncoder struct{}

func (encoder compositionOutputEncoder) Key() string {
	return "generic-output"
}

func (encoder compositionOutputEncoder) Encode(ctx context.Context, req contracts.OutputRequest) (contracts.OutputResult, error) {
	payload := struct {
		RunID       string `json:"run_id"`
		OutputCount int    `json:"output_count"`
	}{
		RunID:       req.Manifest.RunID,
		OutputCount: len(req.NormalizeOutputs),
	}
	encoded, err := json.Marshal(payload)
	if err != nil {
		return contracts.OutputResult{}, err
	}

	return contracts.OutputResult{
		Files: []contracts.OutputFile{
			{
				Name:        "artifacts/generic.json",
				ContentType: "application/json",
				Bytes:       encoded,
			},
		},
	}, nil
}