package main

// log_buffer_test.go — M8-4 ring buffer + level parse + rate limit 的單元測試

import (
	"fmt"
	"testing"
	"time"
)

func TestLogBuffer_AppendAndSnapshot(t *testing.T) {
	b := NewLogBuffer()
	if got := b.Size(); got != 0 {
		t.Fatalf("initial size=%d, want 0", got)
	}

	// 先塞 3 行
	for i := 0; i < 3; i++ {
		b.Append(LogLine{
			Ts:     time.Now().UnixMilli(),
			Stream: "stdout",
			Line:   fmt.Sprintf("line-%d", i),
		})
	}
	if got := b.Size(); got != 3 {
		t.Fatalf("size after 3 appends=%d, want 3", got)
	}

	// Snapshot(0) 應回全部
	all := b.Snapshot(0)
	if len(all) != 3 {
		t.Fatalf("snapshot(0) len=%d, want 3", len(all))
	}
	for i := 0; i < 3; i++ {
		if all[i].Line != fmt.Sprintf("line-%d", i) {
			t.Fatalf("snapshot[%d].Line=%q", i, all[i].Line)
		}
	}

	// Snapshot(2) 應回最後 2 行
	last2 := b.Snapshot(2)
	if len(last2) != 2 {
		t.Fatalf("snapshot(2) len=%d", len(last2))
	}
	if last2[0].Line != "line-1" || last2[1].Line != "line-2" {
		t.Fatalf("snapshot(2) 內容錯誤: %+v", last2)
	}
}

func TestLogBuffer_WrapAround(t *testing.T) {
	b := NewLogBuffer()
	// 塞超過 cap 100 行
	total := logBufferCap + 100
	for i := 0; i < total; i++ {
		b.Append(LogLine{Line: fmt.Sprintf("line-%d", i)})
	}
	if got := b.Size(); got != logBufferCap {
		t.Fatalf("size=%d, want %d", got, logBufferCap)
	}
	if got := b.Dropped(); got != 100 {
		t.Fatalf("dropped=%d, want 100", got)
	}

	// 取最後 3 行，應該是 line-{total-3} ... line-{total-1}
	last3 := b.Snapshot(3)
	if len(last3) != 3 {
		t.Fatalf("snapshot len=%d, want 3", len(last3))
	}
	expected := []string{
		fmt.Sprintf("line-%d", total-3),
		fmt.Sprintf("line-%d", total-2),
		fmt.Sprintf("line-%d", total-1),
	}
	for i, e := range expected {
		if last3[i].Line != e {
			t.Fatalf("last3[%d]=%q, want %q", i, last3[i].Line, e)
		}
	}

	// 取全部應該是 line-100 ... line-2099
	all := b.Snapshot(0)
	if len(all) != logBufferCap {
		t.Fatalf("all len=%d", len(all))
	}
	if all[0].Line != fmt.Sprintf("line-%d", total-logBufferCap) {
		t.Fatalf("all[0]=%q", all[0].Line)
	}
	if all[len(all)-1].Line != fmt.Sprintf("line-%d", total-1) {
		t.Fatalf("all[last]=%q", all[len(all)-1].Line)
	}
}

func TestLogBuffer_Reset(t *testing.T) {
	b := NewLogBuffer()
	for i := 0; i < 10; i++ {
		b.Append(LogLine{Line: fmt.Sprintf("x-%d", i)})
	}
	b.Reset()
	if got := b.Size(); got != 0 {
		t.Fatalf("size after reset=%d, want 0", got)
	}
	snap := b.Snapshot(0)
	if len(snap) != 0 {
		t.Fatalf("snapshot after reset len=%d, want 0", len(snap))
	}
}

func TestLogBuffer_RateLimit(t *testing.T) {
	b := NewLogBuffer()

	// 一秒內前 logRateLimitBurst 次 ShouldEmit 都應為 true
	allowed := 0
	denied := 0
	for i := 0; i < logRateLimitBurst+50; i++ {
		if b.ShouldEmit() {
			allowed++
		} else {
			denied++
		}
	}
	if allowed != logRateLimitBurst {
		t.Fatalf("allowed=%d, want %d", allowed, logRateLimitBurst)
	}
	if denied != 50 {
		t.Fatalf("denied=%d, want 50", denied)
	}
}

func TestParseLogLevel(t *testing.T) {
	cases := []struct {
		line  string
		level string
	}{
		{"2026/04/14 14:23:01 [INFO] server started", "info"},
		{"[WARN] something odd", "warn"},
		{"[ERROR] python died", "error"},
		{"[DEBUG] trace", "debug"},
		{"INFO: message", "info"},
		{"[GIN] 200 | 2.1ms | GET /api/system/info", "info"},
		{"[GIN] 404 | 0.8ms | GET /missing", "warn"},
		{"[GIN] 500 | 12ms | POST /api/boom", "error"},
		{"random text line", ""},
		{"", ""},
	}
	for _, c := range cases {
		got := parseLogLevel(c.line)
		if got != c.level {
			t.Errorf("parseLogLevel(%q)=%q, want %q", c.line, got, c.level)
		}
	}
}