package parser

import (
	"bytes"
	"crypto/sha1"
	"encoding/hex"
	"errors"
	"fmt"
	"math"
	"strconv"
	"strings"

	"git.kleiax.de/homepage/field"
)

type PuzzleBank struct {
	ParserHelper
}

func (pb *PuzzleBank) Parse(data []byte) error {
	if pb == nil {
		return errors.New("nil puzzle bank parser")
	}

	var parsed []*field.Field
	for index, rawLine := range bytes.Split(data, []byte("\n")) {
		lineNumber := index + 1
		line := strings.TrimSpace(string(rawLine))
		if line == "" {
			continue
		}

		columns := strings.Fields(line)
		if len(columns) != 3 {
			return fmt.Errorf("line %d: %w: expected hash, puzzle and rating", lineNumber, ErrInvalidInput)
		}
		if len(columns[0]) != 12 {
			return fmt.Errorf("line %d: %w: hash has %d characters, expected 12", lineNumber, ErrInvalidInput, len(columns[0]))
		}
		if _, err := hex.DecodeString(columns[0]); err != nil {
			return fmt.Errorf("line %d: %w: invalid hash: %v", lineNumber, ErrInvalidInput, err)
		}
		digest := sha1.Sum([]byte(columns[1]))
		if columns[0] != hex.EncodeToString(digest[:])[:12] {
			return fmt.Errorf("line %d: %w: hash does not match puzzle", lineNumber, ErrInvalidInput)
		}

		rating, err := strconv.ParseFloat(columns[2], 64)
		if err != nil {
			return fmt.Errorf("line %d: %w: invalid rating %q: %v", lineNumber, ErrInvalidInput, columns[2], err)
		}
		if rating < 0 || math.IsNaN(rating) || math.IsInf(rating, 0) {
			return fmt.Errorf("line %d: %w: rating must be a finite non-negative number", lineNumber, ErrInvalidInput)
		}
		parsedField, err := classicField(columns[1], rating)
		if err != nil {
			return fmt.Errorf("line %d: %w", lineNumber, err)
		}
		parsed = append(parsed, parsedField)
	}

	if len(parsed) == 0 {
		return ErrNoPuzzles
	}
	pb.fields = parsed
	return nil
}