package agent

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"sync"
	"testing"
	"time"

	"github.com/sipeed/picoclaw/pkg/bus"
	"github.com/sipeed/picoclaw/pkg/config"
	"github.com/sipeed/picoclaw/pkg/providers"
	"github.com/sipeed/picoclaw/pkg/tools"
)

// --- steeringQueue unit tests ---

func TestSteeringQueue_PushDequeue_OneAtATime(t *testing.T) {
	sq := newSteeringQueue(SteeringOneAtATime)

	sq.push(providers.Message{Role: "user", Content: "msg1"})
	sq.push(providers.Message{Role: "user", Content: "msg2"})
	sq.push(providers.Message{Role: "user", Content: "msg3"})

	if sq.len() != 3 {
		t.Fatalf("expected 3 messages, got %d", sq.len())
	}

	msgs := sq.dequeue()
	if len(msgs) != 1 {
		t.Fatalf("expected 1 message in one-at-a-time mode, got %d", len(msgs))
	}
	if msgs[0].Content != "msg1" {
		t.Fatalf("expected 'msg1', got %q", msgs[0].Content)
	}
	if sq.len() != 2 {
		t.Fatalf("expected 2 remaining, got %d", sq.len())
	}

	msgs = sq.dequeue()
	if len(msgs) != 1 || msgs[0].Content != "msg2" {
		t.Fatalf("expected 'msg2', got %v", msgs)
	}

	msgs = sq.dequeue()
	if len(msgs) != 1 || msgs[0].Content != "msg3" {
		t.Fatalf("expected 'msg3', got %v", msgs)
	}

	msgs = sq.dequeue()
	if msgs != nil {
		t.Fatalf("expected nil from empty queue, got %v", msgs)
	}
}

func TestSteeringQueue_PushDequeue_All(t *testing.T) {
	sq := newSteeringQueue(SteeringAll)

	sq.push(providers.Message{Role: "user", Content: "msg1"})
	sq.push(providers.Message{Role: "user", Content: "msg2"})
	sq.push(providers.Message{Role: "user", Content: "msg3"})

	msgs := sq.dequeue()
	if len(msgs) != 3 {
		t.Fatalf("expected 3 messages in all mode, got %d", len(msgs))
	}
	if msgs[0].Content != "msg1" || msgs[1].Content != "msg2" || msgs[2].Content != "msg3" {
		t.Fatalf("unexpected messages: %v", msgs)
	}

	if sq.len() != 0 {
		t.Fatalf("expected 0 remaining, got %d", sq.len())
	}

	msgs = sq.dequeue()
	if msgs != nil {
		t.Fatalf("expected nil from empty queue, got %v", msgs)
	}
}

func TestSteeringQueue_EmptyDequeue(t *testing.T) {
	sq := newSteeringQueue(SteeringOneAtATime)
	if msgs := sq.dequeue(); msgs != nil {
		t.Fatalf("expected nil, got %v", msgs)
	}
}

func TestSteeringQueue_SetMode(t *testing.T) {
	sq := newSteeringQueue(SteeringOneAtATime)
	if sq.getMode() != SteeringOneAtATime {
		t.Fatalf("expected one-at-a-time, got %v", sq.getMode())
	}

	sq.setMode(SteeringAll)
	if sq.getMode() != SteeringAll {
		t.Fatalf("expected all, got %v", sq.getMode())
	}

	// Push two messages and verify all-mode drains them
	sq.push(providers.Message{Role: "user", Content: "a"})
	sq.push(providers.Message{Role: "user", Content: "b"})

	msgs := sq.dequeue()
	if len(msgs) != 2 {
		t.Fatalf("expected 2 messages after mode switch, got %d", len(msgs))
	}
}

func TestSteeringQueue_ConcurrentAccess(t *testing.T) {
	sq := newSteeringQueue(SteeringOneAtATime)

	var wg sync.WaitGroup
	const n = MaxQueueSize

	// Push from multiple goroutines
	for i := 0; i < n; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			sq.push(providers.Message{Role: "user", Content: fmt.Sprintf("msg%d", i)})
		}(i)
	}
	wg.Wait()

	if sq.len() != n {
		t.Fatalf("expected %d messages, got %d", n, sq.len())
	}

	// Drain from multiple goroutines
	var drained int
	var mu sync.Mutex
	for i := 0; i < n; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			if msgs := sq.dequeue(); len(msgs) > 0 {
				mu.Lock()
				drained += len(msgs)
				mu.Unlock()
			}
		}()
	}
	wg.Wait()

	if drained != n {
		t.Fatalf("expected to drain %d messages, got %d", n, drained)
	}
}

func TestSteeringQueue_Overflow(t *testing.T) {
	sq := newSteeringQueue(SteeringOneAtATime)

	// Fill the queue up to its maximum capacity
	for i := 0; i < MaxQueueSize; i++ {
		err := sq.push(providers.Message{Role: "user", Content: fmt.Sprintf("msg%d", i)})
		if err != nil {
			t.Fatalf("unexpected error pushing message %d: %v", i, err)
		}
	}

	// Sanity check: ensure the queue is actually full
	if sq.len() != MaxQueueSize {
		t.Fatalf("expected queue length %d, got %d", MaxQueueSize, sq.len())
	}

	// Attempt to push one more message, which MUST fail
	err := sq.push(providers.Message{Role: "user", Content: "overflow_msg"})

	// Assert the error happened and is the exact one we expect
	if err == nil {
		t.Fatal("expected an error when pushing to a full queue, but got nil")
	}

	expectedErr := "steering queue is full"
	if err.Error() != expectedErr {
		t.Errorf("expected error message %q, got %q", expectedErr, err.Error())
	}
}

func TestParseSteeringMode(t *testing.T) {
	tests := []struct {
		input    string
		expected SteeringMode
	}{
		{"", SteeringOneAtATime},
		{"one-at-a-time", SteeringOneAtATime},
		{"all", SteeringAll},
		{"unknown", SteeringOneAtATime},
	}

	for _, tt := range tests {
		t.Run(tt.input, func(t *testing.T) {
			if got := parseSteeringMode(tt.input); got != tt.expected {
				t.Fatalf("parseSteeringMode(%q) = %v, want %v", tt.input, got, tt.expected)
			}
		})
	}
}

// --- AgentLoop steering integration tests ---

func TestAgentLoop_Steer_Enqueues(t *testing.T) {
	al, cfg, msgBus, provider, cleanup := newTestAgentLoop(t)
	defer cleanup()

	if cfg == nil {
		t.Fatal("expected config to be initialized")
	}
	if msgBus == nil {
		t.Fatal("expected message bus to be initialized")
	}
	if provider == nil {
		t.Fatal("expected provider to be initialized")
	}

	al.Steer(providers.Message{Role: "user", Content: "interrupt me"})

	if al.steering.len() != 1 {
		t.Fatalf("expected 1 steering message, got %d", al.steering.len())
	}

	msgs := al.dequeueSteeringMessages()
	if len(msgs) != 1 || msgs[0].Content != "interrupt me" {
		t.Fatalf("unexpected dequeued message: %v", msgs)
	}
}

func TestAgentLoop_SteeringMode_GetSet(t *testing.T) {
	al, cfg, msgBus, provider, cleanup := newTestAgentLoop(t)
	defer cleanup()

	if cfg == nil {
		t.Fatal("expected config to be initialized")
	}
	if msgBus == nil {
		t.Fatal("expected message bus to be initialized")
	}
	if provider == nil {
		t.Fatal("expected provider to be initialized")
	}

	if al.SteeringMode() != SteeringOneAtATime {
		t.Fatalf("expected default mode one-at-a-time, got %v", al.SteeringMode())
	}

	al.SetSteeringMode(SteeringAll)
	if al.SteeringMode() != SteeringAll {
		t.Fatalf("expected all mode, got %v", al.SteeringMode())
	}
}

func TestAgentLoop_SteeringMode_ConfiguredFromConfig(t *testing.T) {
	tmpDir, err := os.MkdirTemp("", "agent-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	cfg := &config.Config{
		Agents: config.AgentsConfig{
			Defaults: config.AgentDefaults{
				Workspace:         tmpDir,
				Model:             "test-model",
				MaxTokens:         4096,
				MaxToolIterations: 10,
				SteeringMode:      "all",
			},
		},
	}

	msgBus := bus.NewMessageBus()
	provider := &mockProvider{}
	al := NewAgentLoop(cfg, msgBus, provider)

	if al.SteeringMode() != SteeringAll {
		t.Fatalf("expected 'all' mode from config, got %v", al.SteeringMode())
	}
}

func TestAgentLoop_Continue_NoMessages(t *testing.T) {
	al, cfg, msgBus, provider, cleanup := newTestAgentLoop(t)
	defer cleanup()

	if cfg == nil {
		t.Fatal("expected config to be initialized")
	}
	if msgBus == nil {
		t.Fatal("expected message bus to be initialized")
	}
	if provider == nil {
		t.Fatal("expected provider to be initialized")
	}

	resp, err := al.Continue(context.Background(), "test-session", "test", "chat1")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if resp != "" {
		t.Fatalf("expected empty response for no steering messages, got %q", resp)
	}
}

func TestAgentLoop_Continue_WithMessages(t *testing.T) {
	tmpDir, err := os.MkdirTemp("", "agent-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	cfg := &config.Config{
		Agents: config.AgentsConfig{
			Defaults: config.AgentDefaults{
				Workspace:         tmpDir,
				Model:             "test-model",
				MaxTokens:         4096,
				MaxToolIterations: 10,
			},
		},
	}

	msgBus := bus.NewMessageBus()
	provider := &simpleMockProvider{response: "continued response"}
	al := NewAgentLoop(cfg, msgBus, provider)

	al.Steer(providers.Message{Role: "user", Content: "new direction"})

	resp, err := al.Continue(context.Background(), "test-session", "test", "chat1")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if resp != "continued response" {
		t.Fatalf("expected 'continued response', got %q", resp)
	}
}

// slowTool simulates a tool that takes some time to execute.
type slowTool struct {
	name     string
	duration time.Duration
	execCh   chan struct{} // closed when Execute starts
}

func (t *slowTool) Name() string        { return t.name }
func (t *slowTool) Description() string { return "slow tool for testing" }
func (t *slowTool) Parameters() map[string]any {
	return map[string]any{
		"type":       "object",
		"properties": map[string]any{},
	}
}

func (t *slowTool) Execute(ctx context.Context, args map[string]any) *tools.ToolResult {
	if t.execCh != nil {
		close(t.execCh)
	}
	time.Sleep(t.duration)
	return tools.SilentResult(fmt.Sprintf("executed %s", t.name))
}

// toolCallProvider returns an LLM response with tool calls on the first call,
// then a direct response on subsequent calls.
type toolCallProvider struct {
	mu        sync.Mutex
	calls     int
	toolCalls []providers.ToolCall
	finalResp string
}

func (m *toolCallProvider) Chat(
	ctx context.Context,
	messages []providers.Message,
	tools []providers.ToolDefinition,
	model string,
	opts map[string]any,
) (*providers.LLMResponse, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.calls++

	if m.calls == 1 && len(m.toolCalls) > 0 {
		return &providers.LLMResponse{
			Content:   "",
			ToolCalls: m.toolCalls,
		}, nil
	}

	return &providers.LLMResponse{
		Content:   m.finalResp,
		ToolCalls: []providers.ToolCall{},
	}, nil
}

func (m *toolCallProvider) GetDefaultModel() string {
	return "tool-call-mock"
}

func TestAgentLoop_Steering_SkipsRemainingTools(t *testing.T) {
	tmpDir, err := os.MkdirTemp("", "agent-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	cfg := &config.Config{
		Agents: config.AgentsConfig{
			Defaults: config.AgentDefaults{
				Workspace:         tmpDir,
				Model:             "test-model",
				MaxTokens:         4096,
				MaxToolIterations: 10,
			},
		},
	}

	tool1ExecCh := make(chan struct{})
	tool1 := &slowTool{name: "tool_one", duration: 50 * time.Millisecond, execCh: tool1ExecCh}
	tool2 := &slowTool{name: "tool_two", duration: 50 * time.Millisecond}

	provider := &toolCallProvider{
		toolCalls: []providers.ToolCall{
			{
				ID:   "call_1",
				Type: "function",
				Name: "tool_one",
				Function: &providers.FunctionCall{
					Name:      "tool_one",
					Arguments: "{}",
				},
				Arguments: map[string]any{},
			},
			{
				ID:   "call_2",
				Type: "function",
				Name: "tool_two",
				Function: &providers.FunctionCall{
					Name:      "tool_two",
					Arguments: "{}",
				},
				Arguments: map[string]any{},
			},
		},
		finalResp: "steered response",
	}

	msgBus := bus.NewMessageBus()
	al := NewAgentLoop(cfg, msgBus, provider)
	al.RegisterTool(tool1)
	al.RegisterTool(tool2)

	// Start processing in a goroutine
	type result struct {
		resp string
		err  error
	}
	resultCh := make(chan result, 1)

	go func() {
		resp, err := al.ProcessDirectWithChannel(
			context.Background(),
			"do something",
			"test-session",
			"test",
			"chat1",
		)
		resultCh <- result{resp, err}
	}()

	// Wait for tool_one to start executing, then enqueue a steering message
	select {
	case <-tool1ExecCh:
		// tool_one has started executing
	case <-time.After(2 * time.Second):
		t.Fatal("timeout waiting for tool_one to start")
	}

	al.Steer(providers.Message{Role: "user", Content: "change course"})

	// Get the result
	select {
	case r := <-resultCh:
		if r.err != nil {
			t.Fatalf("unexpected error: %v", r.err)
		}
		if r.resp != "steered response" {
			t.Fatalf("expected 'steered response', got %q", r.resp)
		}
	case <-time.After(5 * time.Second):
		t.Fatal("timeout waiting for agent loop to complete")
	}

	// The provider should have been called twice:
	// 1. first call returned tool calls
	// 2. second call (after steering) returned the final response
	provider.mu.Lock()
	calls := provider.calls
	provider.mu.Unlock()
	if calls != 2 {
		t.Fatalf("expected 2 provider calls, got %d", calls)
	}
}

func TestAgentLoop_Steering_InitialPoll(t *testing.T) {
	tmpDir, err := os.MkdirTemp("", "agent-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	cfg := &config.Config{
		Agents: config.AgentsConfig{
			Defaults: config.AgentDefaults{
				Workspace:         tmpDir,
				Model:             "test-model",
				MaxTokens:         4096,
				MaxToolIterations: 10,
			},
		},
	}

	// Provider that captures messages it receives
	var capturedMessages []providers.Message
	var capMu sync.Mutex
	provider := &capturingMockProvider{
		response: "ack",
		captureFn: func(msgs []providers.Message) {
			capMu.Lock()
			capturedMessages = make([]providers.Message, len(msgs))
			copy(capturedMessages, msgs)
			capMu.Unlock()
		},
	}

	msgBus := bus.NewMessageBus()
	al := NewAgentLoop(cfg, msgBus, provider)

	// Enqueue a steering message before processing starts
	al.Steer(providers.Message{Role: "user", Content: "pre-enqueued steering"})

	// Process a normal message - the initial steering poll should inject the steering message
	_, err = al.ProcessDirectWithChannel(
		context.Background(),
		"initial message",
		"test-session",
		"test",
		"chat1",
	)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	// The steering message should have been injected into the conversation
	capMu.Lock()
	msgs := capturedMessages
	capMu.Unlock()

	// Look for the steering message in the captured messages
	found := false
	for _, m := range msgs {
		if m.Content == "pre-enqueued steering" {
			found = true
			break
		}
	}
	if !found {
		t.Fatal("expected steering message to be injected into conversation context")
	}
}

// capturingMockProvider captures messages sent to Chat for inspection.
type capturingMockProvider struct {
	response  string
	calls     int
	captureFn func([]providers.Message)
}

func (m *capturingMockProvider) Chat(
	ctx context.Context,
	messages []providers.Message,
	tools []providers.ToolDefinition,
	model string,
	opts map[string]any,
) (*providers.LLMResponse, error) {
	m.calls++
	if m.captureFn != nil {
		m.captureFn(messages)
	}
	return &providers.LLMResponse{
		Content:   m.response,
		ToolCalls: []providers.ToolCall{},
	}, nil
}

func (m *capturingMockProvider) GetDefaultModel() string {
	return "capturing-mock"
}

func TestAgentLoop_Steering_SkippedToolsHaveErrorResults(t *testing.T) {
	tmpDir, err := os.MkdirTemp("", "agent-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	cfg := &config.Config{
		Agents: config.AgentsConfig{
			Defaults: config.AgentDefaults{
				Workspace:         tmpDir,
				Model:             "test-model",
				MaxTokens:         4096,
				MaxToolIterations: 10,
			},
		},
	}

	execCh := make(chan struct{})
	tool1 := &slowTool{name: "slow_tool", duration: 50 * time.Millisecond, execCh: execCh}
	tool2 := &slowTool{name: "skipped_tool", duration: 50 * time.Millisecond}

	// Provider that captures messages on the second call (after tools)
	var secondCallMessages []providers.Message
	var capMu sync.Mutex
	callCount := 0

	provider := &toolCallProvider{
		toolCalls: []providers.ToolCall{
			{
				ID:   "call_1",
				Type: "function",
				Name: "slow_tool",
				Function: &providers.FunctionCall{
					Name:      "slow_tool",
					Arguments: "{}",
				},
				Arguments: map[string]any{},
			},
			{
				ID:   "call_2",
				Type: "function",
				Name: "skipped_tool",
				Function: &providers.FunctionCall{
					Name:      "skipped_tool",
					Arguments: "{}",
				},
				Arguments: map[string]any{},
			},
		},
		finalResp: "done",
	}

	// Wrap provider to capture messages on second call
	wrappedProvider := &wrappingProvider{
		inner: provider,
		onChat: func(msgs []providers.Message) {
			capMu.Lock()
			callCount++
			if callCount >= 2 {
				secondCallMessages = make([]providers.Message, len(msgs))
				copy(secondCallMessages, msgs)
			}
			capMu.Unlock()
		},
	}

	msgBus := bus.NewMessageBus()
	al := NewAgentLoop(cfg, msgBus, wrappedProvider)
	al.RegisterTool(tool1)
	al.RegisterTool(tool2)

	resultCh := make(chan string, 1)
	go func() {
		resp, _ := al.ProcessDirectWithChannel(
			context.Background(), "go", "test-session", "test", "chat1",
		)
		resultCh <- resp
	}()

	<-execCh
	al.Steer(providers.Message{Role: "user", Content: "interrupt!"})

	select {
	case <-resultCh:
	case <-time.After(5 * time.Second):
		t.Fatal("timeout")
	}

	// Check that the skipped tool result message is in the conversation
	capMu.Lock()
	msgs := secondCallMessages
	capMu.Unlock()

	foundSkipped := false
	for _, m := range msgs {
		if m.Role == "tool" && m.ToolCallID == "call_2" && m.Content == "Skipped due to queued user message." {
			foundSkipped = true
			break
		}
	}
	if !foundSkipped {
		// Log what we actually got
		for i, m := range msgs {
			t.Logf("msg[%d]: role=%s toolCallID=%s content=%s", i, m.Role, m.ToolCallID, truncate(m.Content, 80))
		}
		t.Fatal("expected skipped tool result for call_2")
	}
}

func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n] + "..."
}

// wrappingProvider wraps another provider to hook into Chat calls.
type wrappingProvider struct {
	inner  providers.LLMProvider
	onChat func([]providers.Message)
}

func (w *wrappingProvider) Chat(
	ctx context.Context,
	messages []providers.Message,
	tools []providers.ToolDefinition,
	model string,
	opts map[string]any,
) (*providers.LLMResponse, error) {
	if w.onChat != nil {
		w.onChat(messages)
	}
	return w.inner.Chat(ctx, messages, tools, model, opts)
}

func (w *wrappingProvider) GetDefaultModel() string {
	return w.inner.GetDefaultModel()
}

// Ensure NormalizeToolCall handles our test tool calls.
func init() {
	// This is a no-op init; we just need the tool call tests to work
	// with the proper argument serialization.
	_ = json.Marshal
}