package agent

import (
	"testing"

	"github.com/nextlevelbuilder/goclaw/internal/providers"
)

func TestLimitHistoryTurns_NoLimit(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "m1"},
		{Role: "assistant", Content: "r1"},
		{Role: "user", Content: "m2"},
		{Role: "assistant", Content: "r2"},
	}
	got := limitHistoryTurns(msgs, 0)
	if len(got) != 4 {
		t.Errorf("expected 4 messages, got %d", len(got))
	}
}

func TestLimitHistoryTurns_KeepLast2(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "m1"},
		{Role: "assistant", Content: "r1"},
		{Role: "user", Content: "m2"},
		{Role: "assistant", Content: "r2"},
		{Role: "user", Content: "m3"},
		{Role: "assistant", Content: "r3"},
	}
	got := limitHistoryTurns(msgs, 2)

	if len(got) != 4 {
		t.Fatalf("expected 4 messages, got %d", len(got))
	}
	if got[0].Content != "m2" {
		t.Errorf("expected m2, got %s", got[0].Content)
	}
}

func TestLimitHistoryTurns_KeepLast1(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "m1"},
		{Role: "assistant", Content: "r1"},
		{Role: "user", Content: "m2"},
		{Role: "assistant", Content: "r2"},
	}
	got := limitHistoryTurns(msgs, 1)

	if len(got) != 2 {
		t.Fatalf("expected 2 messages, got %d", len(got))
	}
	if got[0].Content != "m2" {
		t.Errorf("expected m2, got %s", got[0].Content)
	}
}

func TestLimitHistoryTurns_WithToolMessages(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "m1"},
		{Role: "assistant", Content: "r1", ToolCalls: []providers.ToolCall{{ID: "tc1", Name: "read_file"}}},
		{Role: "tool", Content: "result1", ToolCallID: "tc1"},
		{Role: "assistant", Content: "final1"},
		{Role: "user", Content: "m2"},
		{Role: "assistant", Content: "r2"},
	}
	got := limitHistoryTurns(msgs, 1)

	if len(got) != 2 {
		t.Fatalf("expected 2 messages (last turn), got %d", len(got))
	}
	if got[0].Content != "m2" {
		t.Errorf("expected m2, got %s", got[0].Content)
	}
}

func TestLimitHistoryTurns_Empty(t *testing.T) {
	got := limitHistoryTurns(nil, 5)
	if len(got) != 0 {
		t.Errorf("expected empty, got %d", len(got))
	}
}

func TestLimitHistoryTurns_LimitExceedsTotal(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "m1"},
		{Role: "assistant", Content: "r1"},
	}
	got := limitHistoryTurns(msgs, 100)
	if len(got) != 2 {
		t.Errorf("expected 2, got %d", len(got))
	}
}

func TestSanitizeHistory_Empty(t *testing.T) {
	got, _ := sanitizeHistory(nil)
	if len(got) != 0 {
		t.Errorf("expected empty, got %d", len(got))
	}
}

func TestSanitizeHistory_DropsLeadingOrphanedTools(t *testing.T) {
	msgs := []providers.Message{
		{Role: "tool", Content: "orphan1", ToolCallID: "tc1"},
		{Role: "tool", Content: "orphan2", ToolCallID: "tc2"},
		{Role: "user", Content: "hello"},
		{Role: "assistant", Content: "hi"},
	}
	got, _ := sanitizeHistory(msgs)
	if len(got) != 2 {
		t.Fatalf("expected 2 messages, got %d", len(got))
	}
	if got[0].Role != "user" {
		t.Errorf("expected user, got %s", got[0].Role)
	}
}

func TestSanitizeHistory_MatchesToolResults(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "do something"},
		{Role: "assistant", Content: "", ToolCalls: []providers.ToolCall{
			{ID: "tc1", Name: "read_file"},
			{ID: "tc2", Name: "write_file"},
		}},
		{Role: "tool", Content: "file data", ToolCallID: "tc1"},
		{Role: "tool", Content: "written", ToolCallID: "tc2"},
		{Role: "assistant", Content: "done"},
	}
	got, _ := sanitizeHistory(msgs)
	if len(got) != 5 {
		t.Fatalf("expected 5, got %d", len(got))
	}
}

func TestSanitizeHistory_SynthesizesMissingToolResult(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "do something"},
		{Role: "assistant", Content: "", ToolCalls: []providers.ToolCall{
			{ID: "tc1", Name: "read_file"},
			{ID: "tc2", Name: "write_file"},
		}},
		{Role: "tool", Content: "file data", ToolCallID: "tc1"},
		// tc2 is missing
		{Role: "user", Content: "next"},
	}
	got, _ := sanitizeHistory(msgs)

	// user + assistant + tc1 result + synthesized tc2 result + user
	if len(got) != 5 {
		t.Fatalf("expected 5, got %d", len(got))
	}

	// The synthesized message should be for tc2
	foundSynthesized := false
	for _, m := range got {
		if m.ToolCallID == "tc2" && m.Role == "tool" {
			foundSynthesized = true
			if m.Content != "[Tool result missing — session was compacted]" {
				t.Errorf("unexpected synthesized content: %s", m.Content)
			}
		}
	}
	if !foundSynthesized {
		t.Error("missing synthesized tool result for tc2")
	}
}

func TestSanitizeHistory_DropsMismatchedToolResult(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "hello"},
		{Role: "assistant", Content: "", ToolCalls: []providers.ToolCall{
			{ID: "tc1", Name: "read_file"},
		}},
		{Role: "tool", Content: "ok", ToolCallID: "tc1"},
		{Role: "tool", Content: "stray", ToolCallID: "unknown_id"},
		{Role: "user", Content: "next"},
	}
	got, _ := sanitizeHistory(msgs)

	// The stray tool message should be dropped, tc1 result kept
	for _, m := range got {
		if m.ToolCallID == "unknown_id" {
			t.Error("mismatched tool result should be dropped")
		}
	}
}

func TestSanitizeHistory_DropsOrphanedToolMidHistory(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "hello"},
		{Role: "assistant", Content: "hi"},
		{Role: "tool", Content: "orphan mid", ToolCallID: "tc_orphan"},
		{Role: "user", Content: "bye"},
	}
	got, _ := sanitizeHistory(msgs)

	for _, m := range got {
		if m.ToolCallID == "tc_orphan" {
			t.Error("orphaned mid-history tool should be dropped")
		}
	}
	if len(got) != 3 {
		t.Errorf("expected 3, got %d", len(got))
	}
}

func TestEstimateTokens(t *testing.T) {
	msgs := []providers.Message{
		{Role: "user", Content: "Hello world!"},             // 12 chars → ~4 tokens
		{Role: "assistant", Content: "Hi there, how are you?"}, // 22 chars → ~7 tokens
	}
	got := EstimateTokens(msgs)
	if got <= 0 {
		t.Errorf("expected positive token estimate, got %d", got)
	}
}

func TestTruncateStr(t *testing.T) {
	tests := []struct {
		name   string
		input  string
		maxLen int
		want   string
	}{
		{"short", "hello", 10, "hello"},
		{"exact", "hello", 5, "hello"},
		{"truncate", "hello world", 5, "hello..."},
		{"empty", "", 5, ""},
		{"unicode", "héllo wörld", 7, "héllo ..."},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := truncateStr(tt.input, tt.maxLen)
			if tt.maxLen >= len(tt.input) {
				if got != tt.input {
					t.Errorf("got %q, want %q", got, tt.input)
				}
			} else {
				if len(got) == 0 {
					t.Error("truncation returned empty")
				}
			}
		})
	}
}