package cnpj

import (
	"testing"
)

func TestGenerate(t *testing.T) {
	for range 100 {
		cnpj := Generate()
		if len(cnpj) != 14 {
			t.Fatalf("expected 14 digits, got %d: %s", len(cnpj), cnpj)
		}
		for _, c := range cnpj {
			if c < '0' || c > '9' {
				t.Fatalf("non-digit character %c in %s", c, cnpj)
			}
		}
		if isRepetitive(cnpj) {
			t.Fatalf("repetitive CNPJ generated: %s", cnpj)
		}
		if !validateDV(cnpj, false) {
			t.Fatalf("invalid check digits for %s", cnpj)
		}
	}
}

func TestGenerateAlpha(t *testing.T) {
	for range 100 {
		cnpj := GenerateAlpha()
		if len(cnpj) != 14 {
			t.Fatalf("expected 14 chars, got %d: %s", len(cnpj), cnpj)
		}
		for _, c := range cnpj[:12] {
			if !isAlphaNumeric(byte(c)) {
				t.Fatalf("non-alphanumeric character %c in base of %s", c, cnpj)
			}
		}
		for _, c := range cnpj[12:] {
			if c < '0' || c > '9' {
				t.Fatalf("DV must be digit, got %c in %s", c, cnpj)
			}
		}
		if isRepetitive(cnpj) {
			t.Fatalf("repetitive CNPJ generated: %s", cnpj)
		}
		if !validateDV(cnpj, true) {
			t.Fatalf("invalid check digits for %s", cnpj)
		}
	}
}

func TestUniqueness(t *testing.T) {
	seen := make(map[string]bool)
	for range 50 {
		cnpj := Generate()
		if seen[cnpj] {
			t.Fatalf("duplicate CNPJ generated: %s", cnpj)
		}
		seen[cnpj] = true
	}
	for range 50 {
		cnpj := GenerateAlpha()
		if seen[cnpj] {
			t.Fatalf("duplicate CNPJ generated: %s", cnpj)
		}
		seen[cnpj] = true
	}
}

func TestFormat(t *testing.T) {
	tests := []struct {
		input string
		want  string
	}{
		{"12345678000195", "12.345.678/0001-95"},
		{"11111111111111", "11.111.111/1111-11"},
		{"", ""},
		{"123", "123"},
		{"ABCDEFGHIJKLMN", "AB.CDE.FGH/IJKL-MN"},
	}
	for _, tt := range tests {
		got := Format(tt.input)
		if got != tt.want {
			t.Errorf("Format(%q) = %q; want %q", tt.input, got, tt.want)
		}
	}
}

func isAlphaNumeric(c byte) bool {
	return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z')
}

func validateDV(s string, alpha bool) bool {
	if len(s) != 14 {
		return false
	}
	if isRepetitive(s) {
		return false
	}
	dv1 := computeDV(s[:12], cnpjP1, alpha)
	dv2 := computeDV(s[:12]+string(byte('0'+dv1)), cnpjP2, alpha)
	return int(s[12]-'0') == dv1 && int(s[13]-'0') == dv2
}