package server

import (
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestHandleLogsTail_OK(t *testing.T) {
	srv := setupTestServer(t)

	logFile := filepath.Join(t.TempDir(), "test.log")
	lines := make([]string, 25)
	for i := range lines {
		lines[i] = "linija " + string(rune('A'+i))
	}
	os.WriteFile(logFile, []byte(strings.Join(lines, "\n")+"\n"), 0644)
	srv.Config.LogFile = logFile

	req := httptest.NewRequest(http.MethodGet, "/api/logs/tail", nil)
	w := httptest.NewRecorder()
	srv.Router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	got := strings.Split(strings.TrimRight(w.Body.String(), "\n"), "\n")
	if len(got) != maxLogLines {
		t.Fatalf("expected %d lines, got %d", maxLogLines, len(got))
	}
	// First returned line should be line 6 (index 5) since we have 25 lines, tail 20
	if got[0] != "linija F" {
		t.Errorf("expected first line 'linija F', got %q", got[0])
	}
}

func TestHandleLogsTail_LessThan20Lines(t *testing.T) {
	srv := setupTestServer(t)

	logFile := filepath.Join(t.TempDir(), "test.log")
	os.WriteFile(logFile, []byte("prva\ndruga\ntreca\n"), 0644)
	srv.Config.LogFile = logFile

	req := httptest.NewRequest(http.MethodGet, "/api/logs/tail", nil)
	w := httptest.NewRecorder()
	srv.Router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	got := strings.Split(strings.TrimRight(w.Body.String(), "\n"), "\n")
	if len(got) != 3 {
		t.Fatalf("expected 3 lines, got %d", len(got))
	}
}

func TestHandleLogsTail_NoLogFile(t *testing.T) {
	srv := setupTestServer(t)
	// LogFile is empty string by default in test config

	req := httptest.NewRequest(http.MethodGet, "/api/logs/tail", nil)
	w := httptest.NewRecorder()
	srv.Router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if !strings.Contains(w.Body.String(), "KAOS_LOG_FILE") {
		t.Error("expected message about KAOS_LOG_FILE not being set")
	}
}

func TestHandleLogsTail_FileNotFound(t *testing.T) {
	srv := setupTestServer(t)
	srv.Config.LogFile = "/tmp/nonexistent-kaos-test-log-12345.log"

	req := httptest.NewRequest(http.MethodGet, "/api/logs/tail", nil)
	w := httptest.NewRecorder()
	srv.Router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if !strings.Contains(w.Body.String(), "ne postoji") {
		t.Error("expected message about file not existing")
	}
}

func TestHandleLogsTail_Max20Lines(t *testing.T) {
	srv := setupTestServer(t)

	logFile := filepath.Join(t.TempDir(), "test.log")
	lines := make([]string, 100)
	for i := range lines {
		lines[i] = "log line"
	}
	os.WriteFile(logFile, []byte(strings.Join(lines, "\n")+"\n"), 0644)
	srv.Config.LogFile = logFile

	req := httptest.NewRequest(http.MethodGet, "/api/logs/tail", nil)
	w := httptest.NewRecorder()
	srv.Router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	got := strings.Split(strings.TrimRight(w.Body.String(), "\n"), "\n")
	if len(got) > maxLogLines {
		t.Errorf("expected max %d lines, got %d", maxLogLines, len(got))
	}
}

func TestTailLines(t *testing.T) {
	tests := []struct {
		name     string
		text     string
		n        int
		expected int
	}{
		{"empty", "", 20, 1},
		{"less than n", "a\nb\nc", 20, 3},
		{"exact n", "a\nb\nc", 3, 3},
		{"more than n", "a\nb\nc\nd\ne", 3, 3},
		{"trailing newline", "a\nb\nc\n", 2, 2},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := tailLines(tt.text, tt.n)
			if len(got) != tt.expected {
				t.Errorf("tailLines(%q, %d) = %d lines, want %d", tt.text, tt.n, len(got), tt.expected)
			}
		})
	}
}

func TestTailLines_Content(t *testing.T) {
	text := "first\nsecond\nthird\nfourth\nfifth\n"
	got := tailLines(text, 3)

	if len(got) != 3 {
		t.Fatalf("expected 3 lines, got %d", len(got))
	}
	if got[0] != "third" {
		t.Errorf("expected 'third', got %q", got[0])
	}
	if got[1] != "fourth" {
		t.Errorf("expected 'fourth', got %q", got[1])
	}
	if got[2] != "fifth" {
		t.Errorf("expected 'fifth', got %q", got[2])
	}
}