package challenge

import (
	"bufio"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"strconv"
	"strings"
)

func readConfig(r io.Reader) (Config, error) {
	var cfg Config
	if err := json.NewDecoder(r).Decode(&cfg); err != nil {
		return cfg, err
	}
	return cfg, nil
}

func readEvents(r io.Reader) ([]Event, error) {
	var events []Event
	scanner := bufio.NewScanner(r)
	lineNo := 0
	for scanner.Scan() {
		lineNo++
		line := strings.TrimSpace(scanner.Text())
		if line == "" {
			continue
		}
		event, err := parseEvent(line)
		if err != nil {
			return nil, fmt.Errorf("line %d: %w", lineNo, err)
		}
		events = append(events, event)
	}
	return events, scanner.Err()
}

func parseEvent(line string) (Event, error) {
	fields := strings.Fields(line)
	if len(fields) < 3 {
		return Event{}, errors.New("not enough fields")
	}
	if len(fields[0]) != len("[15:04:05]") || fields[0][0] != '[' || fields[0][len(fields[0])-1] != ']' {
		return Event{}, errors.New("bad time format")
	}
	at, err := parseClock(fields[0][1 : len(fields[0])-1])
	if err != nil {
		return Event{}, err
	}
	player, err := strconv.Atoi(fields[1])
	if err != nil {
		return Event{}, err
	}
	id, err := strconv.Atoi(fields[2])
	if err != nil {
		return Event{}, err
	}

	return Event{At: at, Player: player, ID: id, Extra: strings.Join(fields[3:], " ")}, nil
}

func parseNonNegativeInt(value string) (int, bool) {
	if strings.TrimSpace(value) != value || value == "" || strings.Contains(value, " ") {
		return 0, false
	}
	n, err := strconv.Atoi(value)
	return n, err == nil && n >= 0
}