package modelprojection

import (
	"bytes"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/aritmolab/thothii/tools/tht/internal/config"
)

func TestRenderProducesDeterministicCatalogPiAndComposeProjections(t *testing.T) {
	installation := projectionFixture(t)

	first, err := Render(installation)
	if err != nil {
		t.Fatalf("Render() error = %v", err)
	}
	second, err := Render(installation)
	if err != nil {
		t.Fatalf("Render() second error = %v", err)
	}
	if len(first) != 4 {
		t.Fatalf("artifact count = %d, want 4", len(first))
	}
	for path, contents := range first {
		if !bytes.Equal(contents, second[path]) {
			t.Fatalf("artifact %q is not deterministic", path)
		}
	}

	catalog := string(first[CatalogFile])
	for _, expected := range []string{`"id": "local/qwen"`, `"defaultSession": "zai/glm-5.3"`, `"embedding"`} {
		if !strings.Contains(catalog, expected) {
			t.Fatalf("catalog projection missing %s:\n%s", expected, catalog)
		}
	}
	piModels := string(first[PiModelsFile])
	if !strings.Contains(piModels, `"zai"`) || strings.Contains(piModels, `"deepseek"`) {
		t.Fatalf("Pi models projection must contain only custom providers:\n%s", piModels)
	}
	settings := string(first[PiSettingsFile])
	if !strings.Contains(settings, `"deepseek/deepseek-v4-pro"`) || !strings.Contains(settings, `"local/qwen2.5:7b"`) {
		t.Fatalf("Pi settings projection missing enabled session models:\n%s", settings)
	}
	if !strings.Contains(piModels, `"id": "qwen2.5:7b"`) || !strings.Contains(catalog, `"id": "local/qwen"`) {
		t.Fatalf("Pi projection must map canonical catalog keys to upstream model IDs")
	}
	compose := string(first[ComposeFile])
	for _, expected := range []string{"THT_MODEL_CATALOG_FILE", "THT_DEFAULT_SESSION_MODEL", "zai/glm-5.3", "THT_INTERNAL_EMBEDDING_ID", "THT_INTERNAL_EMBEDDING_MODEL", "OLLAMA_MODEL", installation.GeneratedModelCatalogPath()} {
		if !strings.Contains(compose, expected) {
			t.Fatalf("Compose projection missing %q:\n%s", expected, compose)
		}
	}
}

func TestGenerateDoesNotReplaceUnchangedProjection(t *testing.T) {
	installation := projectionFixture(t)
	if err := Generate(installation); err != nil {
		t.Fatalf("Generate() initial error = %v", err)
	}
	paths := []string{
		installation.GeneratedModelCatalogPath(),
		installation.GeneratedPiModelsPath(),
		installation.GeneratedPiSettingsPath(),
		installation.ModelProjectionComposePath(),
	}
	before := make(map[string]os.FileInfo, len(paths))
	for _, path := range paths {
		info, err := os.Stat(path)
		if err != nil {
			t.Fatal(err)
		}
		before[path] = info
	}

	originalRename := renameProjectionDirectory
	t.Cleanup(func() { renameProjectionDirectory = originalRename })
	renames := 0
	renameProjectionDirectory = func(oldPath, newPath string) error {
		renames++
		return os.Rename(oldPath, newPath)
	}
	if err := Generate(installation); err != nil {
		t.Fatalf("Generate() repeated error = %v", err)
	}
	if renames != 0 {
		t.Fatalf("Generate() replaced an unchanged generation with %d renames", renames)
	}
	for _, path := range paths {
		after, err := os.Stat(path)
		if err != nil {
			t.Fatal(err)
		}
		if !os.SameFile(before[path], after) {
			t.Fatalf("Generate() replaced unchanged artifact %q", path)
		}
	}
}

func TestGenerateRestoresWholePreviousGenerationWhenPublishFails(t *testing.T) {
	installation := projectionFixture(t)
	if err := Generate(installation); err != nil {
		t.Fatalf("Generate() initial error = %v", err)
	}
	before := make(map[string][]byte)
	for _, path := range []string{CatalogFile, PiModelsFile, PiSettingsFile, ComposeFile} {
		contents, err := os.ReadFile(filepath.Join(installation.GeneratedDirectory(), filepath.FromSlash(path)))
		if err != nil {
			t.Fatal(err)
		}
		before[path] = contents
	}
	provider := installation.ModelCatalog.Providers["zai"]
	model := provider.Models["glm-5.3"]
	model.Label = "Changed label"
	provider.Models["glm-5.3"] = model
	installation.ModelCatalog.Providers["zai"] = provider

	originalRename := renameProjectionDirectory
	t.Cleanup(func() { renameProjectionDirectory = originalRename })
	renames := 0
	renameProjectionDirectory = func(oldPath, newPath string) error {
		renames++
		if renames == 2 {
			return errors.New("injected publish failure")
		}
		return os.Rename(oldPath, newPath)
	}
	if err := Generate(installation); err == nil {
		t.Fatal("Generate() error = nil, want injected publish failure")
	}
	for path, expected := range before {
		actual, err := os.ReadFile(filepath.Join(installation.GeneratedDirectory(), filepath.FromSlash(path)))
		if err != nil || !bytes.Equal(actual, expected) {
			t.Fatalf("artifact %q changed after failed generation: err=%v", path, err)
		}
	}
}

func TestGeneratePublishesAllArtifactsAndCheckDetectsDrift(t *testing.T) {
	installation := projectionFixture(t)
	if err := Generate(installation); err != nil {
		t.Fatalf("Generate() error = %v", err)
	}
	for _, path := range []string{installation.GeneratedModelCatalogPath(), installation.GeneratedPiModelsPath(), installation.GeneratedPiSettingsPath(), installation.ModelProjectionComposePath()} {
		if info, err := os.Stat(path); err != nil || !info.Mode().IsRegular() {
			t.Fatalf("generated artifact %q: info=%v err=%v", path, info, err)
		}
	}
	if drift, err := Check(installation); err != nil || len(drift) != 0 {
		t.Fatalf("Check() = %v, %v; want no drift", drift, err)
	}
	if err := os.WriteFile(installation.GeneratedPiSettingsPath(), []byte("{}\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if drift, err := Check(installation); err != nil || len(drift) != 1 || drift[0] != PiSettingsFile {
		t.Fatalf("Check() = %v, %v; want [%s]", drift, err, PiSettingsFile)
	}
}

func projectionFixture(t *testing.T) config.Installation {
	t.Helper()
	root := t.TempDir()
	return config.Installation{
		Path: filepath.Join(root, "thothii-installation.yaml"),
		ModelCatalog: config.ModelCatalog{
			Defaults:  config.ModelCatalogDefaults{Session: "zai/glm-5.3", MetadataGeneration: "local/qwen"},
			Embedding: config.ModelCatalogEmbedding{ID: "ollama/qwen3-embedding:0.6b", Dimensions: 1024},
			Providers: map[string]config.ModelProvider{
				"deepseek": {Authentication: config.ModelAuthentication{Mode: "pi_auth"}, Session: &config.ModelSessionAdapter{Mode: "pi_builtin"}, Models: map[string]config.CatalogModel{"deepseek-v4-pro": {Session: &config.SessionModel{}}}},
				"zai":      {Endpoint: &config.ModelEndpoint{BaseURL: "https://api.z.ai/v1"}, Authentication: config.ModelAuthentication{Mode: "none"}, Session: &config.ModelSessionAdapter{Mode: "openai_compatible"}, Models: map[string]config.CatalogModel{"glm-5.3": {Label: "GLM-5.3", Session: &config.SessionModel{Reasoning: true, ContextWindow: 200000, MaxTokens: 131072}}}},
				"local":    {Endpoint: &config.ModelEndpoint{BaseURL: "http://ollama:11434/v1"}, Authentication: config.ModelAuthentication{Mode: "none"}, Session: &config.ModelSessionAdapter{Mode: "openai_compatible"}, MetadataGeneration: &config.ModelMetadataAdapter{LiteLLMProvider: "openai"}, Models: map[string]config.CatalogModel{"qwen": {UpstreamModel: "qwen2.5:7b", Session: &config.SessionModel{ContextWindow: 32768, MaxTokens: 8192}, MetadataGeneration: &config.MetadataGenerationModel{DisableThinking: true}}}},
			},
		},
	}
}