package feed

import (
	"errors"
	"fmt"
	"net/url"
	"regexp"
	"slices"
	"strings"
)

var (
	ErrNoContent      = errors.New("failed to retrieve any content")
	ErrPartialContent = errors.New("failed to retrieve some of the content")
)

func percentChange(current, previous float64) float64 {
	return (current/previous - 1) * 100
}

func extractDomainFromUrl(u string) string {
	if u == "" {
		return ""
	}

	parsed, err := url.Parse(u)

	if err != nil {
		return ""
	}

	return strings.TrimPrefix(strings.ToLower(parsed.Host), "www.")
}

func SvgPolylineCoordsFromYValues(width float64, height float64, values []float64) string {
	if len(values) < 2 {
		return ""
	}

	verticalPadding := height * 0.02
	height -= verticalPadding * 2
	coordinates := make([]string, len(values))
	distanceBetweenPoints := width / float64(len(values)-1)
	min := slices.Min(values)
	max := slices.Max(values)

	for i := range values {
		coordinates[i] = fmt.Sprintf(
			"%.2f,%.2f",
			float64(i)*distanceBetweenPoints,
			((max-values[i])/(max-min))*height+verticalPadding,
		)
	}

	return strings.Join(coordinates, " ")
}

func maybeCopySliceWithoutZeroValues[T int | float64](values []T) []T {
	if len(values) == 0 {
		return values
	}

	for i := range values {
		if values[i] != 0 {
			continue
		}

		c := make([]T, 0, len(values)-1)

		for i := range values {
			if values[i] != 0 {
				c = append(c, values[i])
			}
		}

		return c
	}

	return values
}

func currencyCodeToSymbol(code string) string {
	currencySymbols := map[string]string{
		"btc":  "₿",
		"eth":  "Ξ",
		"ltc":  "Ł",
		"bch":  "₡",
		"bnb":  "Ƀ",
		"eos":  "", // no symbol
		"xrp":  "", // no symbol
		"xlm":  "", // no symbol
		"link": "", // no symbol
		"dot":  "", // no symbol
		"yfi":  "", // no symbol
		"usd":  "$",
		"aed":  "د.إ",
		"ars":  "$",
		"aud":  "AU$",
		"bdt":  "৳",
		"bhd":  ".د.ب",
		"bmd":  "$",
		"brl":  "R$",
		"cad":  "CA$",
		"chf":  "CHF",
		"clp":  "$",
		"cny":  "¥",
		"czk":  "Kč",
		"dkk":  "kr",
		"eur":  "€",
		"gbp":  "£",
		"gel":  "ლ",
		"hkd":  "HK$",
		"huf":  "Ft",
		"idr":  "Rp",
		"ils":  "₪",
		"inr":  "₹",
		"jpy":  "¥",
		"krw":  "₩",
		"kwd":  "د.ك",
		"lkr":  "Rs",
		"mmk":  "K",
		"mxn":  "$",
		"myr":  "RM",
		"ngn":  "₦",
		"nok":  "kr",
		"nzd":  "NZ$",
		"php":  "₱",
		"pkr":  "Rs",
		"pln":  "zł",
		"rub":  "₽",
		"sar":  "ر.س",
		"sek":  "kr",
		"sgd":  "SGD",
		"thb":  "฿",
		"try":  "₺",
		"twd":  "NT$",
		"uah":  "₴",
		"vef":  "Bs",
		"vnd":  "₫",
		"zar":  "R",
		"xdr":  "", // no symbol
		"xag":  "", // no symbol
		"xau":  "", // no symbol
		"bits": "", // no symbol
		"sats": "", // no symbol
	}

	symbol, ok := currencySymbols[code]
	if !ok {
		symbol = strings.ToUpper(code) + " "
	}
	return symbol
}

var urlSchemePattern = regexp.MustCompile(`^[a-z]+:\/\/`)

func stripURLScheme(url string) string {
	return urlSchemePattern.ReplaceAllString(url, "")
}

func limitStringLength(s string, max int) (string, bool) {
	asRunes := []rune(s)

	if len(asRunes) > max {
		return string(asRunes[:max]), true
	}

	return s, false
}