// SPDX-License-Identifier: GPL-3.0-or-later

package eventlog

import (
	"encoding/json"
	"os"
	"path/filepath"
	"testing"
)

func TestReadRecentSpansRotationInChronologicalOrder(t *testing.T) {
	path := filepath.Join(t.TempDir(), "events.jsonl")
	writeLines(t, path+".1", 1, 2, 3)
	writeLines(t, path, 4, 5)
	rows, err := ReadRecent(path, 3)
	if err != nil {
		t.Fatal(err)
	}
	if got := rowSequences(t, rows); len(got) != 3 || got[0] != 3 || got[1] != 4 || got[2] != 5 {
		t.Fatalf("sequences=%v", got)
	}
}

func TestReadRecentReturnsAllWhenUnderLimit(t *testing.T) {
	path := filepath.Join(t.TempDir(), "events.jsonl")
	writeLines(t, path, 7, 8)
	rows, err := ReadRecent(path, 10)
	if err != nil {
		t.Fatal(err)
	}
	if got := rowSequences(t, rows); len(got) != 2 || got[0] != 7 || got[1] != 8 {
		t.Fatalf("sequences=%v", got)
	}
}

func TestReadRecentRejectsCorruptionAndInvalidArguments(t *testing.T) {
	path := filepath.Join(t.TempDir(), "events.jsonl")
	if err := os.WriteFile(path, []byte("{not-json}\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if _, err := ReadRecent(path, 1); err == nil {
		t.Fatal("corrupt log accepted")
	}
	if _, err := ReadRecent("", 1); err == nil {
		t.Fatal("empty path accepted")
	}
	if _, err := ReadRecent(path, 0); err == nil {
		t.Fatal("zero limit accepted")
	}
}

func writeLines(t *testing.T, path string, sequences ...int) {
	t.Helper()
	file, err := os.Create(path)
	if err != nil {
		t.Fatal(err)
	}
	defer file.Close()
	encoder := json.NewEncoder(file)
	for _, sequence := range sequences {
		if err := encoder.Encode(map[string]any{"sequence": sequence}); err != nil {
			t.Fatal(err)
		}
	}
}

func rowSequences(t *testing.T, rows [][]byte) []int {
	t.Helper()
	result := make([]int, 0, len(rows))
	for _, row := range rows {
		var record struct {
			Sequence int `json:"sequence"`
		}
		if err := json.Unmarshal(row, &record); err != nil {
			t.Fatal(err)
		}
		result = append(result, record.Sequence)
	}
	return result
}