package audit

import (
	"context"
	"errors"
	"testing"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
)

// texts 用给定的正文文本构建一个仅含文本消息的上下文。
func texts(role model.Role, bodies ...string) []model.Message {
	out := make([]model.Message, 0, len(bodies))
	for _, b := range bodies {
		out = append(out, model.TextMessage(role, b))
	}
	return out
}

// sameMessage 按角色与拼接后的文本比较两条消息；测试消息都是纯文本，因此这足以判定
// 相等。
func sameMessage(a, b model.Message) bool {
	return a.Role == b.Role && messageText(a) == messageText(b)
}

func TestNewContextAuditor_Snapshot(t *testing.T) {
	t.Parallel()

	msgs := texts(model.RoleUser, "alpha", "bravo", "charlie")
	aud := NewContextAuditor(msgs)

	// 构造之后再改调用方的切片，不得影响审计结果。
	msgs[0].Role = model.RoleSystem
	got := aud.Full()
	if got[0].Role != model.RoleUser {
		t.Fatalf("snapshot leaked caller mutation: role = %q, want %q", got[0].Role, model.RoleUser)
	}
}

func TestFull_ReturnsDefensiveCopy(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "alpha", "bravo"))

	got := aud.Full()
	got[0].Role = model.RoleSystem
	got[1].Role = model.RoleSystem

	fresh := aud.Full()
	if fresh[0].Role != model.RoleUser || fresh[1].Role != model.RoleUser {
		t.Fatalf("Full leaked mutation of its returned copy: %+v", fresh)
	}
}

func TestTail(t *testing.T) {
	t.Parallel()

	full := texts(model.RoleUser, "alpha", "bravo", "charlie", "delta")
	aud := NewContextAuditor(full)

	tests := []struct {
		name string
		n    int
		want []string
	}{
		{name: "zero returns empty", n: 0, want: nil},
		{name: "negative returns empty", n: -1, want: nil},
		{name: "single", n: 1, want: []string{"delta"}},
		{name: "pair", n: 2, want: []string{"charlie", "delta"}},
		{name: "exact length", n: 4, want: []string{"alpha", "bravo", "charlie", "delta"}},
		{name: "beyond length clamps to full", n: 9, want: []string{"alpha", "bravo", "charlie", "delta"}},
	}

	for _, tt := range tests {
		tt := tt
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()
			got := aud.Tail(tt.n)
			if len(got) != len(tt.want) {
				t.Fatalf("Tail(%d) length = %d, want %d", tt.n, len(got), len(tt.want))
			}
			for i := range got {
				if got[i].Role != model.RoleUser || messageText(got[i]) != tt.want[i] {
					t.Fatalf("Tail(%d)[%d] = %q/%s, want text %q", tt.n, i, messageText(got[i]), got[i].Role, tt.want[i])
				}
			}
		})
	}
}

func TestKeyword_LocateWithSurroundings(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "alpha", "bravo", "charlie"))

	loc, err := aud.Keyword(context.Background(), "rav")
	if err != nil {
		t.Fatalf("Keyword unexpected error: %v", err)
	}
	if loc == nil {
		t.Fatal("Keyword returned nil for a present match")
	}
	if loc.Line != 2 {
		t.Fatalf("Line = %d, want 2", loc.Line)
	}
	if len(loc.Surrounding) != 3 {
		t.Fatalf("Surrounding length = %d, want 3", len(loc.Surrounding))
	}
	if !sameMessage(loc.Surrounding[1], model.TextMessage(model.RoleUser, "bravo")) {
		t.Fatalf("matched message missing from window: %+v", loc.Surrounding)
	}
	if !sameMessage(loc.Surrounding[0], model.TextMessage(model.RoleUser, "alpha")) {
		t.Fatalf("above-message missing from window: %+v", loc.Surrounding)
	}
	if !sameMessage(loc.Surrounding[2], model.TextMessage(model.RoleUser, "charlie")) {
		t.Fatalf("below-message missing from window: %+v", loc.Surrounding)
	}
}

func TestKeyword_Edges(t *testing.T) {
	t.Parallel()

	t.Run("first message has no above-neighbor", func(t *testing.T) {
		t.Parallel()
		aud := NewContextAuditor(texts(model.RoleUser, "alpha", "bravo"))
		loc, err := aud.Keyword(context.Background(), "alp")
		if err != nil {
			t.Fatalf("Keyword unexpected error: %v", err)
		}
		if loc.Line != 1 {
			t.Fatalf("Line = %d, want 1", loc.Line)
		}
		if len(loc.Surrounding) != 2 {
			t.Fatalf("Surrounding length = %d, want 2", len(loc.Surrounding))
		}
	})

	t.Run("last message has no below-neighbor", func(t *testing.T) {
		t.Parallel()
		aud := NewContextAuditor(texts(model.RoleUser, "alpha", "bravo"))
		loc, err := aud.Keyword(context.Background(), "bra")
		if err != nil {
			t.Fatalf("Keyword unexpected error: %v", err)
		}
		if loc.Line != 2 {
			t.Fatalf("Line = %d, want 2", loc.Line)
		}
		if len(loc.Surrounding) != 2 {
			t.Fatalf("Surrounding length = %d, want 2", len(loc.Surrounding))
		}
	})
}

func TestKeyword_CaseInsensitive(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "alpha", "bravo"))
	loc, err := aud.Keyword(context.Background(), "BRAVO")
	if err != nil {
		t.Fatalf("Keyword unexpected error: %v", err)
	}
	if loc == nil || loc.Line != 2 {
		t.Fatalf("case-insensitive match failed: line = %d", loc.Line)
	}
}

func TestKeyword_NoMatch(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "alpha", "bravo"))
	loc, err := aud.Keyword(context.Background(), "zzz")
	if err != nil {
		t.Fatalf("Keyword unexpected error: %v", err)
	}
	if loc != nil {
		t.Fatalf("Keyword = %+v, want nil for a missing match", loc)
	}
}

func TestKeyword_EmptyAndBlankQuery(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "alpha"))
	for _, q := range []string{"", "   "} {
		_, err := aud.Keyword(context.Background(), q)
		if !errors.Is(err, ErrQueryEmpty) {
			t.Fatalf("Keyword(%q) error = %v, want ErrQueryEmpty", q, err)
		}
	}
}

func TestKeyword_CanceledContext(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "alpha"))
	ctx, cancel := context.WithCancel(context.Background())
	cancel()

	_, err := aud.Keyword(ctx, "alpha")
	if !errors.Is(err, context.Canceled) {
		t.Fatalf("Keyword error = %v, want context.Canceled", err)
	}
}

func TestKeyword_FirstMatchOnly(t *testing.T) {
	t.Parallel()

	aud := NewContextAuditor(texts(model.RoleUser, "foo", "bar", "foo"))
	loc, err := aud.Keyword(context.Background(), "foo")
	if err != nil {
		t.Fatalf("Keyword unexpected error: %v", err)
	}
	if loc.Line != 1 {
		t.Fatalf("Line = %d, want 1 (earliest match)", loc.Line)
	}
}

func TestKeyword_IgnoresImagePayload(t *testing.T) {
	t.Parallel()

	msgs := []model.Message{
		model.TextMessage(model.RoleUser, "alpha"),
		model.ImageMessage(model.RoleUser, "", "http://example.com/bravo.png"),
	}
	aud := NewContextAuditor(msgs)

	loc, err := aud.Keyword(context.Background(), "bravo")
	if err != nil {
		t.Fatalf("Keyword unexpected error: %v", err)
	}
	if loc != nil {
		t.Fatalf("Keyword matched an image URL (ignored): %+v", loc)
	}

	loc, err = aud.Keyword(context.Background(), "alpha")
	if err != nil {
		t.Fatalf("Keyword unexpected error: %v", err)
	}
	if loc == nil || loc.Line != 1 {
		t.Fatalf("text-part match failed: line = %d", loc.Line)
	}
}