package providers

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

// minimalPNGForProviders is a 1x1 transparent PNG in base64 used by native image tests.
const minimalPNGForProviders = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg=="

// mockImageServer returns a test server that captures request bodies and returns a
// minimal successful image generation response. The captured pointer is written on
// each request.
func mockImageServer(t *testing.T, captured *[]byte) *httptest.Server {
	t.Helper()
	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			t.Errorf("read body: %v", err)
			http.Error(w, "read error", http.StatusInternalServerError)
			return
		}
		*captured = body

		resp := map[string]any{
			"id":     "resp_test",
			"status": "completed",
			"output": []map[string]any{
				{
					"type":          "image_generation_call",
					"result":        minimalPNGForProviders,
					"output_format": "png",
				},
			},
		}
		w.Header().Set("Content-Type", "application/json")
		if err := json.NewEncoder(w).Encode(resp); err != nil {
			t.Errorf("encode response: %v", err)
		}
	}))
}

// TestCodexGenerateImage_BuildsNativeRequest verifies that GenerateImage sends the
// correct JSON body to the Responses API: model, stream:false, input, tools, and
// tool_choice. The test captures the raw request body from a mock server and
// asserts each required field is present and well-formed.
//
// Sub-cases:
//   - Default (empty ImageModel) → tools[0].model == DefaultImageModel
//   - Legacy (ImageModel: "gpt-image-1.5") → tools[0].model == "gpt-image-1.5"
//   - Rejected (ImageModel: "dall-e-3") → GenerateImage returns error containing "unsupported image model"
func TestCodexGenerateImage_BuildsNativeRequest(t *testing.T) {
	var captured []byte
	server := mockImageServer(t, &captured)
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	req := NativeImageRequest{
		Model:        "gpt-image-2",
		Prompt:       "A red circle on a white background",
		AspectRatio:  "16:9",
		OutputFormat: "png",
	}
	result, err := p.GenerateImage(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateImage returned error: %v", err)
	}
	if len(result.Data) == 0 {
		t.Fatal("GenerateImage returned empty Data")
	}

	// Verify outbound request body shape.
	var body map[string]any
	if err := json.Unmarshal(captured, &body); err != nil {
		t.Fatalf("unmarshal captured body: %v", err)
	}

	// model field (outer Responses API model, not image model)
	if model, _ := body["model"].(string); model != "gpt-image-2" {
		t.Errorf("body[model] = %q, want %q", model, "gpt-image-2")
	}

	// Responses API requires stream:true — non-streaming requests are rejected with
	// HTTP 400 "Stream must be set to true". Final image is assembled from SSE events.
	if stream, _ := body["stream"].(bool); !stream {
		t.Error("body[stream] must be true (Responses API rejects stream:false)")
	}

	// instructions is required by Responses API — must be non-empty.
	if instr, _ := body["instructions"].(string); instr == "" {
		t.Error("body[instructions] must be non-empty (Responses API rejects requests without instructions)")
	}

	// input must be an array with one user message
	inputs, ok := body["input"].([]any)
	if !ok || len(inputs) != 1 {
		t.Fatalf("body[input]: expected []any length 1, got %T len %d", body["input"], len(inputs))
	}
	userMsg, ok := inputs[0].(map[string]any)
	if !ok {
		t.Fatalf("input[0] is not a map: %T", inputs[0])
	}
	if role, _ := userMsg["role"].(string); role != "user" {
		t.Errorf("input[0].role = %q, want %q", role, "user")
	}
	contents, ok := userMsg["content"].([]any)
	if !ok || len(contents) != 1 {
		t.Fatalf("input[0].content: expected []any length 1, got %T len %d", userMsg["content"], len(contents))
	}
	contentPart, ok := contents[0].(map[string]any)
	if !ok {
		t.Fatalf("content[0] is not a map: %T", contents[0])
	}
	if typ, _ := contentPart["type"].(string); typ != "input_text" {
		t.Errorf("content[0].type = %q, want %q", typ, "input_text")
	}
	if text, _ := contentPart["text"].(string); text != req.Prompt {
		t.Errorf("content[0].text = %q, want %q", text, req.Prompt)
	}

	// tools must contain one image_generation entry
	tools, ok := body["tools"].([]any)
	if !ok || len(tools) != 1 {
		t.Fatalf("body[tools]: expected []any length 1, got %T len %d", body["tools"], len(tools))
	}
	tool, ok := tools[0].(map[string]any)
	if !ok {
		t.Fatalf("tools[0] is not a map: %T", tools[0])
	}
	if typ, _ := tool["type"].(string); typ != "image_generation" {
		t.Errorf("tools[0].type = %q, want %q", typ, "image_generation")
	}
	// size should map to 1792x1024 for 16:9
	wantSize := SizeFromAspect("16:9")
	if size, _ := tool["size"].(string); size != wantSize {
		t.Errorf("tools[0].size = %q, want %q", size, wantSize)
	}
	if fmt.Sprint(tool["output_format"]) != "png" {
		t.Errorf("tools[0].output_format = %v, want png", tool["output_format"])
	}
	// tools[0].model must be gpt-image-2 (default when ImageModel is empty)
	if imgModel, _ := tool["model"].(string); imgModel != DefaultImageModel {
		t.Errorf("tools[0].model = %q, want %q (default)", imgModel, DefaultImageModel)
	}

	// tool_choice must force image_generation
	toolChoice, ok := body["tool_choice"].(map[string]any)
	if !ok {
		t.Fatalf("body[tool_choice] is not a map: %T", body["tool_choice"])
	}
	if typ, _ := toolChoice["type"].(string); typ != "image_generation" {
		t.Errorf("tool_choice.type = %q, want %q", typ, "image_generation")
	}
}

// TestCodexGenerateImage_ImageModelDefault verifies that an empty ImageModel results
// in DefaultImageModel in the outbound tools[0].model field.
func TestCodexGenerateImage_ImageModelDefault(t *testing.T) {
	var captured []byte
	server := mockImageServer(t, &captured)
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	_, err := p.GenerateImage(context.Background(), NativeImageRequest{
		Prompt:      "test",
		ImageModel:  "", // explicitly empty - should fall back to DefaultImageModel
		AspectRatio: "1:1",
	})
	if err != nil {
		t.Fatalf("GenerateImage returned error: %v", err)
	}

	var body map[string]any
	if err := json.Unmarshal(captured, &body); err != nil {
		t.Fatalf("unmarshal captured body: %v", err)
	}
	tools, _ := body["tools"].([]any)
	if len(tools) == 0 {
		t.Fatal("tools array is empty")
	}
	tool, _ := tools[0].(map[string]any)
	if imgModel, _ := tool["model"].(string); imgModel != DefaultImageModel {
		t.Errorf("tools[0].model = %q, want %q (default)", imgModel, DefaultImageModel)
	}
}

// TestCodexGenerateImage_ImageModelLegacy verifies that ImageModel "gpt-image-1.5"
// is forwarded to the outbound tools[0].model field.
func TestCodexGenerateImage_ImageModelLegacy(t *testing.T) {
	var captured []byte
	server := mockImageServer(t, &captured)
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	_, err := p.GenerateImage(context.Background(), NativeImageRequest{
		Prompt:      "test",
		ImageModel:  "gpt-image-1.5",
		AspectRatio: "1:1",
	})
	if err != nil {
		t.Fatalf("GenerateImage returned error: %v", err)
	}

	var body map[string]any
	if err := json.Unmarshal(captured, &body); err != nil {
		t.Fatalf("unmarshal captured body: %v", err)
	}
	tools, _ := body["tools"].([]any)
	if len(tools) == 0 {
		t.Fatal("tools array is empty")
	}
	tool, _ := tools[0].(map[string]any)
	if imgModel, _ := tool["model"].(string); imgModel != "gpt-image-1.5" {
		t.Errorf("tools[0].model = %q, want gpt-image-1.5 (legacy)", imgModel)
	}
}

// TestCodexGenerateImage_ImageModelRejected verifies that an unsupported image model
// causes GenerateImage to return an error containing "unsupported image model" before
// making any HTTP request.
func TestCodexGenerateImage_ImageModelRejected(t *testing.T) {
	requestMade := false
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		requestMade = true
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	_, err := p.GenerateImage(context.Background(), NativeImageRequest{
		Prompt:     "test",
		ImageModel: "dall-e-3",
	})
	if err == nil {
		t.Fatal("expected error for unsupported image model, got nil")
	}
	if !strings.Contains(err.Error(), "unsupported image model") {
		t.Errorf("error %q does not contain 'unsupported image model'", err.Error())
	}
	if requestMade {
		t.Error("HTTP request was made despite invalid image model (should have been rejected before the request)")
	}
}

// TestCodexGenerateImage_SSEFallback verifies that GenerateImage correctly parses
// an SSE-format response when the server returns streamed lines instead of a JSON blob.
func TestCodexGenerateImage_SSEFallback(t *testing.T) {
	imgB64 := minimalPNGForProviders

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		// Emit a response.completed SSE event with an image_generation_call.
		ev := codexSSEEvent{
			Type: "response.completed",
			Response: &codexAPIResponse{
				ID:     "resp_sse",
				Status: "completed",
				Output: []codexItem{
					{
						ID:           "ig_1",
						Type:         "image_generation_call",
						OutputFormat: "png",
						Result:       imgB64,
					},
				},
				Usage: &codexUsage{InputTokens: 5, OutputTokens: 5, TotalTokens: 10},
			},
		}
		b, _ := json.Marshal(ev)
		fmt.Fprintf(w, "data: %s\n\n", b)
		fmt.Fprint(w, "data: [DONE]\n\n")
	}))
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	result, err := p.GenerateImage(context.Background(), NativeImageRequest{
		Prompt:       "A blue square",
		OutputFormat: "png",
	})
	if err != nil {
		t.Fatalf("GenerateImage SSE fallback: %v", err)
	}
	if result.MimeType != "image/png" {
		t.Errorf("MimeType = %q, want image/png", result.MimeType)
	}
	want, _ := base64.StdEncoding.DecodeString(imgB64)
	if len(result.Data) != len(want) {
		t.Errorf("Data length = %d, want %d", len(result.Data), len(want))
	}
	if result.Usage == nil {
		t.Error("Usage is nil")
	} else if result.Usage.TotalTokens != 10 {
		t.Errorf("Usage.TotalTokens = %d, want 10", result.Usage.TotalTokens)
	}
}

// TestCodexGenerateImage_NoPrompt verifies that an empty prompt returns an error
// before making any HTTP request.
func TestCodexGenerateImage_NoPrompt(t *testing.T) {
	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, "http://localhost", "gpt-image-2")
	p.retryConfig.Attempts = 1

	_, err := p.GenerateImage(context.Background(), NativeImageRequest{Prompt: ""})
	if err == nil {
		t.Fatal("expected error for empty prompt, got nil")
	}
}

// TestSizeFromAspect verifies the aspect ratio → pixel dimension mapping.
func TestSizeFromAspect(t *testing.T) {
	cases := []struct {
		ratio string
		want  string
	}{
		{"1:1", "1024x1024"},
		{"16:9", "1792x1024"},
		{"9:16", "1024x1792"},
		{"4:3", "1365x1024"},
		{"3:4", "1024x1365"},
		{"", "1024x1024"},
		{"custom", "1024x1024"},
	}
	for _, tc := range cases {
		got := SizeFromAspect(tc.ratio)
		if got != tc.want {
			t.Errorf("SizeFromAspect(%q) = %q, want %q", tc.ratio, got, tc.want)
		}
	}
}

// TestCodexGenerateImage_WithReferenceImage verifies that passing a single RefImage
// embeds the image in the input content and does not populate input_reference in tools[0].
func TestCodexGenerateImage_WithReferenceImage(t *testing.T) {
	var captured []byte
	server := mockImageServer(t, &captured)
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	req := NativeImageRequest{
		Model:        "gpt-image-2",
		Prompt:       "A red circle",
		RefImages: []RefImage{
			{
				URL: "https://example.com/ref.png",
			},
		},
		AspectRatio:  "1:1",
		OutputFormat: "png",
	}

	_, err := p.GenerateImage(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateImage returned error: %v", err)
	}

	var body map[string]any
	if err := json.Unmarshal(captured, &body); err != nil {
		t.Fatalf("unmarshal captured body: %v", err)
	}

	// 1. Verify input contains input_image and input_text in user content
	inputs, ok := body["input"].([]any)
	if !ok || len(inputs) != 1 {
		t.Fatalf("body[input]: expected []any length 1, got %T len %d", body["input"], len(inputs))
	}
	userMsg, ok := inputs[0].(map[string]any)
	if !ok {
		t.Fatalf("inputs[0] is not a map")
	}
	contents, ok := userMsg["content"].([]any)
	if !ok || len(contents) != 2 {
		t.Fatalf("content: expected []any length 2, got %T len %d", userMsg["content"], len(contents))
	}

	imgPart, ok := contents[0].(map[string]any)
	if !ok {
		t.Fatalf("contents[0] is not a map")
	}
	if imgPart["type"] != "input_image" || imgPart["image_url"] != "https://example.com/ref.png" {
		t.Errorf("expected input_image with url, got: %v", imgPart)
	}

	textPart, ok := contents[1].(map[string]any)
	if !ok {
		t.Fatalf("contents[1] is not a map")
	}
	if textPart["type"] != "input_text" || textPart["text"] != "A red circle" {
		t.Errorf("expected input_text with prompt, got: %v", textPart)
	}

	// 2. Verify tools[0] does not contain input_reference
	tools, ok := body["tools"].([]any)
	if !ok || len(tools) != 1 {
		t.Fatalf("tools shape invalid")
	}
	tool, ok := tools[0].(map[string]any)
	if !ok {
		t.Fatalf("tools[0] not map")
	}
	if _, has := tool["input_reference"]; has {
		t.Error("image_generation tool must not contain 'input_reference' field")
	}
}

// TestCodexGenerateImage_WithMultipleReferenceImages verifies that passing multiple RefImages
// embeds all of them in the input content in the correct order.
func TestCodexGenerateImage_WithMultipleReferenceImages(t *testing.T) {
	var captured []byte
	server := mockImageServer(t, &captured)
	defer server.Close()

	p := NewCodexProvider("codex-test", &staticTokenSource{token: "tok"}, server.URL, "gpt-image-2")
	p.retryConfig.Attempts = 1

	req := NativeImageRequest{
		Model:        "gpt-image-2",
		Prompt:       "A red circle",
		RefImages: []RefImage{
			{
				URL: "https://example.com/ref1.png",
			},
			{
				Base64:   "b64data",
				MimeType: "image/jpeg",
			},
		},
		AspectRatio:  "1:1",
		OutputFormat: "png",
	}

	_, err := p.GenerateImage(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateImage returned error: %v", err)
	}

	var body map[string]any
	if err := json.Unmarshal(captured, &body); err != nil {
		t.Fatalf("unmarshal captured body: %v", err)
	}

	inputs, _ := body["input"].([]any)
	userMsg, _ := inputs[0].(map[string]any)
	contents, _ := userMsg["content"].([]any)

	// Expected: 2 images + 1 text prompt = 3 content parts
	if len(contents) != 3 {
		t.Fatalf("content: expected []any length 3, got len %d", len(contents))
	}

	imgPart1, _ := contents[0].(map[string]any)
	if imgPart1["type"] != "input_image" || imgPart1["image_url"] != "https://example.com/ref1.png" {
		t.Errorf("expected first input_image with url, got: %v", imgPart1)
	}

	imgPart2, _ := contents[1].(map[string]any)
	if imgPart2["type"] != "input_image" || imgPart2["image_url"] != "data:image/jpeg;base64,b64data" {
		t.Errorf("expected second input_image with base64 data url, got: %v", imgPart2)
	}

	textPart, _ := contents[2].(map[string]any)
	if textPart["type"] != "input_text" || textPart["text"] != "A red circle" {
		t.Errorf("expected input_text with prompt, got: %v", textPart)
	}
}