package model

import (
	"bytes"
	"context"
	"log/slog"
	"net/http"
	"strings"
	"testing"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
)

// captureLog returns a logger writing text records into a buffer, plus the
// buffer, so a test can assert the WARN an adapter emits.
func captureLog() (*slog.Logger, *bytes.Buffer) {
	buf := &bytes.Buffer{}
	return slog.New(slog.NewTextHandler(buf, &slog.HandlerOptions{Level: slog.LevelDebug})), buf
}

// boolPtr is a convenience for the tri-state Thinking.Enable.
func boolPtr(v bool) *bool { return &v }

// TestAnthropicChat_ThinkingBudgetLeavesRoomForTheAnswer is the design/04 §3.2
// red line: a budget large enough to eat max_tokens must not be sent as-is —
// the adapter raises max_tokens so thinking and the visible answer both fit, and
// it logs the adjustment (never a silent rewrite).
func TestAnthropicChat_ThinkingBudgetLeavesRoomForTheAnswer(t *testing.T) {
	t.Parallel()
	ch := make(chan anthropicCaptured, 1)
	srv := newAnthropicServer(t, http.StatusOK, "application/json", anthropicTextResponse, ch)
	log, buf := captureLog()
	ad := NewAnthropicChat(
		config.LLMConfig{AnthropicBaseURL: srv.URL, AnthropicModel: "claude-test"},
		WithAnthropicLogger(log))

	const budget = 4096
	// max_tokens equals the budget: without the guard the whole budget would be
	// consumed by thinking and the answer would come back empty.
	if _, err := ad.Chat(context.Background(), Request{
		Model:     "claude-test",
		Messages:  []Message{TextMessage(RoleUser, "hi")},
		MaxTokens: budget,
		Thinking:  &Thinking{BudgetTokens: budget},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	body := (<-ch).body
	think, ok := body["thinking"].(map[string]any)
	if !ok {
		t.Fatalf("body.thinking = %v, want an enabled directive", body["thinking"])
	}
	if think["type"] != anthropicThinkingTypeEnabled {
		t.Errorf("thinking.type = %v, want %q", think["type"], anthropicThinkingTypeEnabled)
	}
	gotBudget, _ := think["budget_tokens"].(float64)
	maxTokens, _ := body["max_tokens"].(float64)
	if int(gotBudget) != budget {
		t.Errorf("thinking.budget_tokens = %v, want %d", gotBudget, budget)
	}
	if maxTokens <= gotBudget {
		t.Fatalf("max_tokens = %v, want > budget_tokens %v (thinking would eat the answer)", maxTokens, gotBudget)
	}
	if maxTokens < gotBudget+anthropicThinkingBodyReserve {
		t.Errorf("max_tokens = %v, want >= budget %v + body reserve %d", maxTokens, gotBudget, anthropicThinkingBodyReserve)
	}
	if !strings.Contains(buf.String(), "max_tokens raised") {
		t.Errorf("log = %q, want a WARN explaining the max_tokens raise", buf.String())
	}
}

// TestAnthropicChat_ThinkingBudgetBelowMaxTokensUnchanged pins the non-saturated
// case: when the caller's max_tokens already leaves room, it is sent untouched
// and the budget stays strictly below it.
func TestAnthropicChat_ThinkingBudgetBelowMaxTokensUnchanged(t *testing.T) {
	t.Parallel()
	ch := make(chan anthropicCaptured, 1)
	srv := newAnthropicServer(t, http.StatusOK, "application/json", anthropicTextResponse, ch)
	log, buf := captureLog()
	ad := NewAnthropicChat(
		config.LLMConfig{AnthropicBaseURL: srv.URL, AnthropicModel: "claude-test"},
		WithAnthropicLogger(log))

	if _, err := ad.Chat(context.Background(), Request{
		Model:     "claude-test",
		Messages:  []Message{TextMessage(RoleUser, "hi")},
		MaxTokens: anthropicDefaultMaxTokens,
		Thinking:  &Thinking{BudgetTokens: 4096},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	body := (<-ch).body
	think := body["thinking"].(map[string]any)
	gotBudget, _ := think["budget_tokens"].(float64)
	maxTokens, _ := body["max_tokens"].(float64)
	if maxTokens != float64(anthropicDefaultMaxTokens) {
		t.Errorf("max_tokens = %v, want the requested %d (unchanged)", maxTokens, anthropicDefaultMaxTokens)
	}
	if gotBudget >= maxTokens {
		t.Errorf("budget_tokens %v >= max_tokens %v", gotBudget, maxTokens)
	}
	if strings.Contains(buf.String(), "max_tokens raised") {
		t.Errorf("unexpected adjustment log: %q", buf.String())
	}
}

// TestAnthropicChat_ThinkingDisabledOmitsField asserts the explicit off switch
// sends no thinking directive at all (Anthropic treats a missing field as off).
func TestAnthropicChat_ThinkingDisabledOmitsField(t *testing.T) {
	t.Parallel()
	ch := make(chan anthropicCaptured, 1)
	srv := newAnthropicServer(t, http.StatusOK, "application/json", anthropicTextResponse, ch)
	ad := NewAnthropicChat(config.LLMConfig{AnthropicBaseURL: srv.URL, AnthropicModel: "claude-test"})

	if _, err := ad.Chat(context.Background(), Request{
		Model:    "claude-test",
		Messages: []Message{TextMessage(RoleUser, "hi")},
		Thinking: &Thinking{BudgetTokens: 4096, Enable: boolPtr(false)},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	if body := (<-ch).body; body["thinking"] != nil {
		t.Fatalf("body.thinking = %v, want the field omitted", body["thinking"])
	}
}

// TestAnthropicChat_ThinkingBudgetRaisedToProtocolMinimum asserts a budget below
// the API minimum is raised (sending it as-is would 400) and reported.
func TestAnthropicChat_ThinkingBudgetRaisedToProtocolMinimum(t *testing.T) {
	t.Parallel()
	ch := make(chan anthropicCaptured, 1)
	srv := newAnthropicServer(t, http.StatusOK, "application/json", anthropicTextResponse, ch)
	log, buf := captureLog()
	ad := NewAnthropicChat(
		config.LLMConfig{AnthropicBaseURL: srv.URL, AnthropicModel: "claude-test"},
		WithAnthropicLogger(log))

	if _, err := ad.Chat(context.Background(), Request{
		Model:    "claude-test",
		Messages: []Message{TextMessage(RoleUser, "hi")},
		Thinking: &Thinking{BudgetTokens: 512},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	think := (<-ch).body["thinking"].(map[string]any)
	if got, _ := think["budget_tokens"].(float64); int(got) != anthropicMinThinkingBudget {
		t.Errorf("thinking.budget_tokens = %v, want the minimum %d", got, anthropicMinThinkingBudget)
	}
	if !strings.Contains(buf.String(), "protocol minimum") {
		t.Errorf("log = %q, want a WARN about the minimum budget", buf.String())
	}
}

// TestOpenAIChat_ReasoningEffortPassthrough asserts a supported tier on a known
// provider is forwarded verbatim, with no warning.
func TestOpenAIChat_ReasoningEffortPassthrough(t *testing.T) {
	t.Parallel()
	ch := make(chan capturedRequest, 1)
	srv := newCompletionServer(t, http.StatusOK, "application/json", okCompletion, ch)
	log, buf := captureLog()
	ad := NewOpenAIChat(config.LLMConfig{BaseURL: srv.URL, Model: "gpt-test"}, WithOpenAILogger(log))

	if _, err := ad.Chat(context.Background(), Request{
		Model:           "gpt-4o",
		Messages:        []Message{TextMessage(RoleUser, "hi")},
		ReasoningEffort: "high",
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	if got := (<-ch).body["reasoning_effort"]; got != "high" {
		t.Fatalf("body.reasoning_effort = %v, want high", got)
	}
	if buf.Len() != 0 {
		t.Errorf("unexpected log for a supported value: %q", buf.String())
	}
}

// TestOpenAIChat_ReasoningEffortAliasMappedForDeepSeek asserts a DeepSeek
// compatibility alias is normalized to the tier the service applies (medium →
// high per the official mapping table) and reported, never graded down to a
// weaker tier of our own choosing.
func TestOpenAIChat_ReasoningEffortAliasMappedForDeepSeek(t *testing.T) {
	t.Parallel()
	ch := make(chan capturedRequest, 1)
	srv := newCompletionServer(t, http.StatusOK, "application/json", okCompletion, ch)
	log, buf := captureLog()
	ad := NewOpenAIChat(config.LLMConfig{BaseURL: srv.URL, Model: "deepseek-flash"}, WithOpenAILogger(log))

	if _, err := ad.Chat(context.Background(), Request{
		Model:           "deepseek-flash",
		Messages:        []Message{TextMessage(RoleUser, "hi")},
		ReasoningEffort: "medium",
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	if got := (<-ch).body["reasoning_effort"]; got != "high" {
		t.Fatalf("body.reasoning_effort = %v, want the officially mapped high", got)
	}
	rec := buf.String()
	for _, want := range []string{"level=WARN", "reasoning_effort", "deepseek", "medium", "high"} {
		if !strings.Contains(rec, want) {
			t.Errorf("log %q missing %q", rec, want)
		}
	}
}

// TestOpenAIChat_ReasoningEffortDroppedForUnknownProvider asserts an
// unrecognized provider/model leaves the request untouched and reports the
// ignored field (design/04 §3.2: never silently ineffective).
func TestOpenAIChat_ReasoningEffortDroppedForUnknownProvider(t *testing.T) {
	t.Parallel()
	ch := make(chan capturedRequest, 1)
	srv := newCompletionServer(t, http.StatusOK, "application/json", okCompletion, ch)
	log, buf := captureLog()
	ad := NewOpenAIChat(config.LLMConfig{BaseURL: srv.URL, Model: "mystery-1"}, WithOpenAILogger(log))

	if _, err := ad.Chat(context.Background(), Request{
		Model:           "mystery-1",
		Messages:        []Message{TextMessage(RoleUser, "hi")},
		ReasoningEffort: "high",
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	body := (<-ch).body
	if _, present := body["reasoning_effort"]; present {
		t.Fatalf("body.reasoning_effort = %v, want the field dropped", body["reasoning_effort"])
	}
	rec := buf.String()
	for _, want := range []string{"level=WARN", "reasoning_effort", "unknown", "high"} {
		if !strings.Contains(rec, want) {
			t.Errorf("log %q missing %q", rec, want)
		}
	}
}

// TestOpenAIChat_QwenEnableThinkingReportedNotForwarded documents the deliberate
// choice for the Qwen3 hard switch: the OpenAI-compatible protocol has no
// portable wire shape for enable_thinking, so this version reports it and leaves
// the request byte-identical instead of guessing a shape that could 400.
func TestOpenAIChat_QwenEnableThinkingReportedNotForwarded(t *testing.T) {
	t.Parallel()
	ch := make(chan capturedRequest, 1)
	srv := newCompletionServer(t, http.StatusOK, "application/json", okCompletion, ch)
	log, buf := captureLog()
	ad := NewOpenAIChat(config.LLMConfig{BaseURL: srv.URL, Model: "qwen3-max"}, WithOpenAILogger(log))

	plain := make(chan capturedRequest, 1)
	plainSrv := newCompletionServer(t, http.StatusOK, "application/json", okCompletion, plain)
	plainAd := NewOpenAIChat(config.LLMConfig{BaseURL: plainSrv.URL, Model: "qwen3-max"})
	if _, err := plainAd.Chat(context.Background(), Request{
		Model:    "qwen3-max",
		Messages: []Message{TextMessage(RoleUser, "hi")},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	if _, err := ad.Chat(context.Background(), Request{
		Model:    "qwen3-max",
		Messages: []Message{TextMessage(RoleUser, "hi")},
		Thinking: &Thinking{Enable: boolPtr(false)},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	body := (<-ch).body
	for _, key := range []string{"enable_thinking", "chat_template_kwargs", "extra_body", "thinking"} {
		if _, present := body[key]; present {
			t.Errorf("body.%s = %v, want the request unchanged", key, body[key])
		}
	}
	if len(body) != len((<-plain).body) {
		t.Errorf("request shape changed with a thinking directive: %v", body)
	}
	rec := buf.String()
	for _, want := range []string{"level=WARN", "enable_thinking", "qwen"} {
		if !strings.Contains(rec, want) {
			t.Errorf("log %q missing %q", rec, want)
		}
	}
}

// TestOpenAIChat_ThinkingBudgetReportedIgnored asserts a token budget (an
// Anthropic-style directive) is reported as unmappable on an OpenAI-compatible
// endpoint rather than silently dropped.
func TestOpenAIChat_ThinkingBudgetReportedIgnored(t *testing.T) {
	t.Parallel()
	ch := make(chan capturedRequest, 1)
	srv := newCompletionServer(t, http.StatusOK, "application/json", okCompletion, ch)
	log, buf := captureLog()
	ad := NewOpenAIChat(config.LLMConfig{BaseURL: srv.URL, Model: "gpt-4o"}, WithOpenAILogger(log))

	if _, err := ad.Chat(context.Background(), Request{
		Model:    "gpt-4o",
		Messages: []Message{TextMessage(RoleUser, "hi")},
		Thinking: &Thinking{BudgetTokens: 8192},
	}, Options{}); err != nil {
		t.Fatalf("Chat error: %v", err)
	}
	if _, present := (<-ch).body["thinking"]; present {
		t.Fatal("body.thinking was sent to an OpenAI-compatible endpoint")
	}
	rec := buf.String()
	for _, want := range []string{"level=WARN", "thinking.budget_tokens", "gpt"} {
		if !strings.Contains(rec, want) {
			t.Errorf("log %q missing %q", rec, want)
		}
	}
}

// TestAnthropicChatStream_ThinkingBudgetLeavesRoomForTheAnswer runs the same
// red-line check on the streaming path, which builds its own request body.
func TestAnthropicChatStream_ThinkingBudgetLeavesRoomForTheAnswer(t *testing.T) {
	t.Parallel()
	ch := make(chan anthropicCaptured, 1)
	const sse = "event: message_start\ndata: {\"type\":\"message_start\"}\n\n" +
		"event: content_block_start\ndata: {\"type\":\"content_block_start\",\"index\":0,\"content_block\":{\"type\":\"text\",\"text\":\"\"}}\n\n" +
		"event: content_block_delta\ndata: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\"hi\"}}\n\n" +
		"event: message_stop\ndata: {\"type\":\"message_stop\"}\n\n"
	srv := newAnthropicServer(t, http.StatusOK, "text/event-stream", sse, ch)
	ad := NewAnthropicChat(config.LLMConfig{AnthropicBaseURL: srv.URL, AnthropicModel: "claude-test"})

	if _, err := ad.ChatStream(context.Background(), Request{
		Model:     "claude-test",
		Messages:  []Message{TextMessage(RoleUser, "hi")},
		MaxTokens: 2048,
		Thinking:  &Thinking{BudgetTokens: 2048},
	}, func(StreamEvent) {}); err != nil {
		t.Fatalf("ChatStream error: %v", err)
	}
	body := (<-ch).body
	think, ok := body["thinking"].(map[string]any)
	if !ok {
		t.Fatalf("stream body.thinking = %v, want an enabled directive", body["thinking"])
	}
	gotBudget, _ := think["budget_tokens"].(float64)
	maxTokens, _ := body["max_tokens"].(float64)
	if gotBudget >= maxTokens {
		t.Fatalf("stream max_tokens = %v, want > budget_tokens %v", maxTokens, gotBudget)
	}
}

// TestReasoningVendorFor_Classification locks the vendor detection the whitelist
// depends on, including the fallback to the base URL.
func TestReasoningVendorFor_Classification(t *testing.T) {
	t.Parallel()

	cases := []struct {
		model   string
		baseURL string
		want    reasoningVendor
	}{
		{model: "deepseek-v4-pro", want: vendorDeepSeek},
		{model: "Qwen3-Max", want: vendorQwen},
		{model: "gpt-4o", want: vendorOpenAI},
		{model: "o3-mini", want: vendorOpenAI},
		{model: "chatgpt-4o-latest", want: vendorOpenAI},
		{model: "claude-sonnet-4", baseURL: "https://api.openai.com/v1", want: vendorOpenAI},
		{model: "qwen-plus", baseURL: "https://dashscope.aliyuncs.com/compatible-mode/v1", want: vendorQwen},
		{model: "some-model", baseURL: "https://api.deepseek.com/v1", want: vendorDeepSeek},
		{model: "some-model", baseURL: "http://localhost:8000/v1", want: vendorUnknown},
	}
	for _, tt := range cases {
		if got := reasoningVendorFor(tt.model, tt.baseURL); got != tt.want {
			t.Errorf("reasoningVendorFor(%q, %q) = %q, want %q", tt.model, tt.baseURL, got, tt.want)
		}
	}
}