Pineapple Punch - makes about 25 cups

1 large ripe pineapple
2 750-ml bottles dry white wine
1/2 cup brandy
1/4 cup confectioners sugar
1 cup granulated sugar
1 cup water
2 chilled 750-ml bottles Champagne

Cut off and discard top of pineapple. Cut off rind and cut rind into 2-inch pieces. Quarter pineapple lengthwise and cut away core, then cut core into 2-inch pieces. Blend rind and core to a coarse purée in a food processor, in batches if necessary.
Put pineapple purée in a bowl and stir in white wine. Chill, covered, 1 hour.
Cut remaining pineapple into 1/3-inch dice and stir with brandy and confectioners sugar in another bowl. Macerate, covered and chilled, stirring occasionally, 1 hour.
While pineapple is macerating, bring granulated sugar and water to a boil, stirring until sugar is dissolved, then boil syrup over moderate heat, undisturbed, until it registers 230°F on candy thermometer. Cool syrup.
Pour wine mixture through a large fine sieve into a punch bowl set in cracked ice and stir in syrup, pineapple with liquid, and Champagne.