package anthropic

import (
	"testing"

	anth "github.com/liushuangls/go-anthropic/v2"

	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/provider"
)

// TestBuildRequest_MultiSystemUsedWhenSystemPresent verifies that after the
// refactor, the Anthropic provider uses MultiSystem (multi-part) rather than
// the flat System string when a system message is present. This is
// behavior-preserving — the upstream client's MarshalJSON prefers
// MultiSystem when both are set.
func TestBuildRequest_MultiSystemUsedWhenSystemPresent(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "system", Content: "you are helpful"},
			{Role: "user", Content: "hello"},
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.MultiSystem) != 1 {
		t.Fatalf("expected 1 MultiSystem part, got %d", len(anthReq.MultiSystem))
	}
	if anthReq.MultiSystem[0].Text != "you are helpful" {
		t.Errorf("expected MultiSystem text 'you are helpful', got %q", anthReq.MultiSystem[0].Text)
	}
	if anthReq.MultiSystem[0].Type != "text" {
		t.Errorf("expected MultiSystem type 'text', got %q", anthReq.MultiSystem[0].Type)
	}
	if anthReq.System != "" {
		t.Errorf("expected System string to be empty when MultiSystem is used, got %q", anthReq.System)
	}
}

// TestBuildRequest_MultipleSystemMessagesConcatenated verifies that multiple
// system messages are joined into a single MultiSystem part (preserving
// existing newline-joined behavior from the old code).
func TestBuildRequest_MultipleSystemMessagesConcatenated(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "system", Content: "part A"},
			{Role: "system", Content: "part B"},
			{Role: "user", Content: "hello"},
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.MultiSystem) != 1 {
		t.Fatalf("expected 1 MultiSystem part after concat, got %d", len(anthReq.MultiSystem))
	}
	expected := "part A\npart B"
	if anthReq.MultiSystem[0].Text != expected {
		t.Errorf("expected MultiSystem text %q, got %q", expected, anthReq.MultiSystem[0].Text)
	}
}

// TestBuildRequest_NoSystemMessage verifies that when there's no system
// message, both System and MultiSystem are empty.
func TestBuildRequest_NoSystemMessage(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "user", Content: "hello"},
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.MultiSystem) != 0 {
		t.Errorf("expected empty MultiSystem when no system message, got %d parts", len(anthReq.MultiSystem))
	}
	if anthReq.System != "" {
		t.Errorf("expected empty System string, got %q", anthReq.System)
	}
}

// TestBuildRequest_CacheHints_Tools verifies that the last tool definition
// gets a cache_control marker when CacheHints.CacheTools is set.
func TestBuildRequest_CacheHints_Tools(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Tools: []provider.ToolDef{
			{Name: "a", Description: "tool a", Schema: map[string]any{}},
			{Name: "b", Description: "tool b", Schema: map[string]any{}},
		},
		Messages: []provider.Message{{Role: "user", Content: "hi"}},
		CacheHints: &provider.CacheHints{
			CacheTools:                true,
			LastCacheableMessageIndex: -1,
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.Tools) != 2 {
		t.Fatalf("expected 2 tools, got %d", len(anthReq.Tools))
	}
	if anthReq.Tools[0].CacheControl != nil {
		t.Error("expected first tool to have no CacheControl")
	}
	if anthReq.Tools[1].CacheControl == nil {
		t.Fatal("expected last tool to have CacheControl")
	}
	if anthReq.Tools[1].CacheControl.Type != anth.CacheControlTypeEphemeral {
		t.Errorf("expected last tool CacheControl type ephemeral, got %q", anthReq.Tools[1].CacheControl.Type)
	}
}

// TestBuildRequest_CacheHints_System verifies that the final system part
// gets a cache_control marker when CacheHints.CacheSystem is set.
func TestBuildRequest_CacheHints_System(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "system", Content: "you are helpful"},
			{Role: "user", Content: "hi"},
		},
		CacheHints: &provider.CacheHints{
			CacheSystem:               true,
			LastCacheableMessageIndex: -1,
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.MultiSystem) != 1 {
		t.Fatalf("expected 1 MultiSystem part, got %d", len(anthReq.MultiSystem))
	}
	if anthReq.MultiSystem[0].CacheControl == nil {
		t.Fatal("expected system part to have CacheControl")
	}
	if anthReq.MultiSystem[0].CacheControl.Type != anth.CacheControlTypeEphemeral {
		t.Errorf("expected system CacheControl type ephemeral, got %q", anthReq.MultiSystem[0].CacheControl.Type)
	}
}

// TestBuildRequest_CacheHints_LastMessage verifies that the last content
// block of the target message receives a cache_control marker.
func TestBuildRequest_CacheHints_LastMessage(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "user", Content: "first turn"},
			{Role: "assistant", Content: "ok"},
			{Role: "user", Content: "second turn"},
		},
		CacheHints: &provider.CacheHints{
			LastCacheableMessageIndex: 2,
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.Messages) != 3 {
		t.Fatalf("expected 3 messages, got %d", len(anthReq.Messages))
	}
	last := anthReq.Messages[2]
	if len(last.Content) != 1 {
		t.Fatalf("expected 1 content block on last message, got %d", len(last.Content))
	}
	if last.Content[0].CacheControl == nil {
		t.Fatal("expected CacheControl on last content block of last message")
	}
	if anthReq.Messages[0].Content[0].CacheControl != nil {
		t.Error("expected no CacheControl on first message")
	}
}

// TestBuildRequest_CacheHints_IndexDriftFromMerge verifies that when the
// provider merges consecutive same-role messages, the cache breakpoint
// lands on the correct merged output message.
//
// Scenario: source [user:"a", user:"b", assistant:"c", user:"d"].
// After merging: msgs[0]=user[a,b], msgs[1]=assistant[c], msgs[2]=user[d].
// With LastCacheableMessageIndex=3 (source idx of "d"), marker should land on
// msgs[2].Content[0].
func TestBuildRequest_CacheHints_IndexDriftFromMerge(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "user", Content: "a"},
			{Role: "user", Content: "b"},
			{Role: "assistant", Content: "c"},
			{Role: "user", Content: "d"},
		},
		CacheHints: &provider.CacheHints{
			LastCacheableMessageIndex: 3,
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.Messages) != 3 {
		t.Fatalf("expected 3 merged messages, got %d", len(anthReq.Messages))
	}
	if len(anthReq.Messages[2].Content) != 1 {
		t.Fatalf("expected 1 content block on merged user, got %d", len(anthReq.Messages[2].Content))
	}
	if anthReq.Messages[2].Content[0].CacheControl == nil {
		t.Fatal("expected CacheControl on last content block of merged user message")
	}
	for i, cb := range anthReq.Messages[0].Content {
		if cb.CacheControl != nil {
			t.Errorf("expected no CacheControl on anthReq.Messages[0].Content[%d]", i)
		}
	}
}

// TestBuildRequest_CacheHints_IndexDriftTargetIsMerged: scenario where
// LastCacheableMessageIndex points into a message that was merged.
// Source [user:"a", user:"b"] → msgs[0]=user[a,b]. Index 1 should land on
// msgs[0].Content[1] ("b").
func TestBuildRequest_CacheHints_IndexDriftTargetIsMerged(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "user", Content: "a"},
			{Role: "user", Content: "b"},
		},
		CacheHints: &provider.CacheHints{
			LastCacheableMessageIndex: 1,
		},
	}
	anthReq := p.buildRequest(req)

	if len(anthReq.Messages) != 1 {
		t.Fatalf("expected 1 merged message, got %d", len(anthReq.Messages))
	}
	if len(anthReq.Messages[0].Content) != 2 {
		t.Fatalf("expected 2 content blocks after merge, got %d", len(anthReq.Messages[0].Content))
	}
	if anthReq.Messages[0].Content[0].CacheControl != nil {
		t.Error("expected no CacheControl on first content block (source index 0)")
	}
	if anthReq.Messages[0].Content[1].CacheControl == nil {
		t.Fatal("expected CacheControl on second content block (source index 1)")
	}
}

// TestBuildRequest_CacheHints_AllThree: tools + system + last-message all
// receive markers in a single request.
func TestBuildRequest_CacheHints_AllThree(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Tools: []provider.ToolDef{
			{Name: "t1", Description: "tool", Schema: map[string]any{}},
		},
		Messages: []provider.Message{
			{Role: "system", Content: "be helpful"},
			{Role: "user", Content: "hi"},
		},
		CacheHints: &provider.CacheHints{
			CacheTools:                true,
			CacheSystem:               true,
			LastCacheableMessageIndex: 1,
		},
	}
	anthReq := p.buildRequest(req)

	if anthReq.Tools[0].CacheControl == nil {
		t.Error("expected tool CacheControl")
	}
	if anthReq.MultiSystem[0].CacheControl == nil {
		t.Error("expected system CacheControl")
	}
	if len(anthReq.Messages) != 1 {
		t.Fatalf("expected 1 message, got %d", len(anthReq.Messages))
	}
	if anthReq.Messages[0].Content[0].CacheControl == nil {
		t.Error("expected user-message CacheControl")
	}
}

// TestBuildRequest_CacheHints_Nil: nil CacheHints → no markers.
func TestBuildRequest_CacheHints_Nil(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Tools: []provider.ToolDef{
			{Name: "t", Description: "d", Schema: map[string]any{}},
		},
		Messages: []provider.Message{
			{Role: "system", Content: "s"},
			{Role: "user", Content: "hi"},
		},
	}
	anthReq := p.buildRequest(req)

	if anthReq.Tools[0].CacheControl != nil {
		t.Error("expected no tool CacheControl with nil hints")
	}
	if len(anthReq.MultiSystem) == 1 && anthReq.MultiSystem[0].CacheControl != nil {
		t.Error("expected no system CacheControl with nil hints")
	}
	for i, m := range anthReq.Messages {
		for j, cb := range m.Content {
			if cb.CacheControl != nil {
				t.Errorf("expected no CacheControl on anthReq.Messages[%d].Content[%d]", i, j)
			}
		}
	}
}

// TestBuildRequest_CacheHints_ToolResultMessage: marker lands on the right
// tool-result message.
func TestBuildRequest_CacheHints_ToolResultMessage(t *testing.T) {
	p := New("test-key")
	req := provider.Request{
		Model: "claude-sonnet-4-6",
		Messages: []provider.Message{
			{Role: "user", Content: "use the tool"},
			{Role: "assistant", Content: "", ToolCalls: []provider.ToolCall{
				{ID: "tc1", Name: "x", Arguments: "{}"},
			}},
			{Role: "tool", Content: "result data", ToolCallID: "tc1"},
		},
		CacheHints: &provider.CacheHints{
			LastCacheableMessageIndex: 2,
		},
	}
	anthReq := p.buildRequest(req)

	var toolMsg *anth.Message
	for i := range anthReq.Messages {
		for _, cb := range anthReq.Messages[i].Content {
			if cb.MessageContentToolResult != nil {
				toolMsg = &anthReq.Messages[i]
				break
			}
		}
	}
	if toolMsg == nil {
		t.Fatal("expected to find tool-result message")
	}
	lastBlock := toolMsg.Content[len(toolMsg.Content)-1]
	if lastBlock.CacheControl == nil {
		t.Error("expected CacheControl on last content block of tool-result message")
	}
}