package latex

import (
	"regexp"
	"strings"
)

func ConvertLaTeXToASCII(input string) string {
	s := input

	replacements := []struct {
		pattern *regexp.Regexp
		replace string
	}{
		// Fractions: \frac{a}{b} -> (a)/(b)
		{regexp.MustCompile(`\\frac\{([^{}]+)\}\{([^{}]+)\}`), `($1)/($2)`},

		// Square roots: \sqrt{x} -> sqrt(x)
		{regexp.MustCompile(`\\sqrt\{([^{}]+)\}`), `sqrt($1)`},

		// Powers: x^{y} -> x^y
		{regexp.MustCompile(`\{?\^\{([^{}]+)\}\}?`), `^$1`},

		// Subscripts: x_{i} -> x_i
		{regexp.MustCompile(`_\{([^{}]+)\}`), `_$1`},

		// Greek letters (common subset)
		{regexp.MustCompile(`\\alpha`), "alpha"},
		{regexp.MustCompile(`\\beta`), "beta"},
		{regexp.MustCompile(`\\gamma`), "gamma"},
		{regexp.MustCompile(`\\delta`), "delta"},
		{regexp.MustCompile(`\\theta`), "theta"},
		{regexp.MustCompile(`\\pi`), "pi"},
		{regexp.MustCompile(`\\lambda`), "lambda"},

		// Common symbols
		{regexp.MustCompile(`\\times`), "*"},
		{regexp.MustCompile(`\\cdot`), "*"},
		{regexp.MustCompile(`\\pm`), "+/-"},
		{regexp.MustCompile(`\\leq`), "<="},
		{regexp.MustCompile(`\\geq`), ">="},
		{regexp.MustCompile(`\\neq`), "!="},

		// Remove LaTeX math wrappers
		{regexp.MustCompile(`\\left|\\right`), ""},
		{regexp.MustCompile(`\\[|\\]|\$`), ""},
	}

	for _, r := range replacements {
		s = r.pattern.ReplaceAllString(s, r.replace)
	}

	// Clean extra spaces
	s = strings.TrimSpace(strings.Join(strings.Fields(s), " "))

	return s
}