package opslog

import (
"encoding/json"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"time"
)

// LogEntry is the detailed record written to .jsonl files and flushed to the DB.
type LogEntry struct {
	IterationID  int64     `json:"iteration_id"`
	DryRun       bool      `json:"dry_run"`
	Operation    string    `json:"operation"`
	Filepath     string    `json:"filepath"`
	SizeBefore   int64     `json:"size_before"`
	SizeAfter    int64     `json:"size_after"`
	MD5Before    string    `json:"md5_before"`
	MD5After     string    `json:"md5_after"`
	StartedAt    time.Time `json:"started_at"`
	EndedAt      time.Time `json:"ended_at"`
	Status       string    `json:"status"`
	ErrorMessage string    `json:"error_message"`
}

// OpRecord describes a single file operation performed during a sync pass.
type OpRecord struct {
	IterID  int64     `json:"iter_id"`
	RelPath string    `json:"rel_path"`
	Action  string    `json:"action"` // create | update | delete | skip | fail
	Bytes   int64     `json:"bytes,omitempty"`
	ErrMsg  string    `json:"error,omitempty"`
	At      time.Time `json:"at"`
	Owner   string    `json:"owner,omitempty"`
}

// Writer serialises OpRecords as newline-delimited JSON.
type Writer struct {
file *os.File // non-nil when opened via Open
enc  *json.Encoder
}

// NewWriter wraps any io.Writer (useful for testing).
func NewWriter(w io.Writer) *Writer {
return &Writer{enc: json.NewEncoder(w)}
}

// Open creates logDir if needed and opens a new .jsonl log file named after
// pair, direction and the current UTC timestamp.
func Open(logDir, pair, direction string) (*Writer, error) {
if err := os.MkdirAll(logDir, 0o755); err != nil {
return nil, fmt.Errorf("opslog: create dir: %w", err)
}
ts := strings.ReplaceAll(time.Now().UTC().Format(time.RFC3339), ":", "-")
name := fmt.Sprintf("opslog-%s-%s-%s.jsonl", pair, direction, ts)
f, err := os.Create(filepath.Join(logDir, name))
if err != nil {
return nil, fmt.Errorf("opslog: open file: %w", err)
}
return &Writer{file: f, enc: json.NewEncoder(f)}, nil
}

// WriteOp stamps rec with the current UTC time and encodes it as JSON.
func (w *Writer) WriteOp(rec OpRecord) error {
rec.At = time.Now().UTC()
return w.enc.Encode(rec)
}

// Close closes the underlying file if the Writer was created with Open.
func (w *Writer) Close() error {
if w.file != nil {
return w.file.Close()
}
return nil
}

// Path returns the log file path when the Writer was created with Open.
func (w *Writer) Path() string {
if w.file != nil {
return w.file.Name()
}
return ""
}