package mock

import (
	"encoding/csv"
	"encoding/json"
	"fmt"
	"io"
	"sort"
	"strings"
)

func logExportFormat(value string) (string, error) {
	value = strings.ToLower(strings.TrimSpace(value))
	if value == "" {
		value = "jsonl"
	}
	if value != "jsonl" && value != "json" && value != "csv" {
		return "", fmt.Errorf("format must be csv, json, or jsonl")
	}
	return value, nil
}
func writeLogExport(w io.Writer, format string, rows []any) error {
	format, err := logExportFormat(format)
	if err != nil {
		return err
	}
	if format == "json" {
		return json.NewEncoder(w).Encode(rows)
	}
	if format == "jsonl" {
		e := json.NewEncoder(w)
		for _, row := range rows {
			if err := e.Encode(row); err != nil {
				return err
			}
		}
		return nil
	}
	objects := make([]map[string]json.RawMessage, 0, len(rows))
	keys := map[string]bool{}
	for _, row := range rows {
		b, err := json.Marshal(row)
		if err != nil {
			return err
		}
		var object map[string]json.RawMessage
		if err = json.Unmarshal(b, &object); err != nil {
			return err
		}
		objects = append(objects, object)
		for key := range object {
			keys[key] = true
		}
	}
	columns := make([]string, 0, len(keys))
	for key := range keys {
		columns = append(columns, key)
	}
	sort.Strings(columns)
	if _, err := io.WriteString(w, "\ufeff"); err != nil {
		return err
	}
	writer := csv.NewWriter(w)
	if err := writer.Write(columns); err != nil {
		return err
	}
	for _, object := range objects {
		values := make([]string, len(columns))
		for i, key := range columns {
			raw := object[key]
			if len(raw) == 0 {
				continue
			}
			var value string
			if json.Unmarshal(raw, &value) != nil {
				value = string(raw)
			}
			trimmed := strings.TrimLeft(value, " \t\r\n")
			if len(trimmed) > 0 && strings.ContainsRune("=+-@", rune(trimmed[0])) {
				value = "'" + value
			}
			values[i] = value
		}
		if err := writer.Write(values); err != nil {
			return err
		}
	}
	writer.Flush()
	return writer.Error()
}