package main

import (
	"os"
	"io"
	"index/suffixarray"
	"regexp"
	"log"
)

func main() {
	idx := os.Args[1] + ".suf"
	f, err := os.Open(os.Args[1])
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	regexps := []*regexp.Regexp{}
	for _, re := range os.Args[2:] {
		re = "(?m:" + re + ")"
		re_compiled, err := regexp.Compile(re)
		if err != nil {
			log.Fatal(re, ": ", err)
		}

		regexps = append(regexps, re_compiled)
	}

	idxf, err := os.Open(idx)
	if err != nil {
		log.Fatal(err)
	}
	defer idxf.Close()

	var index suffixarray.Index
	err = index.Read(idxf)
	if err != nil {
		log.Fatal("reading ", idxf.Name(), ": ", err)
	}

	data := []byte{}

	for _, re_compiled := range regexps {
		for _, match := range index.FindAllIndex(re_compiled, -1) {
			missing := match[1] - len(data)
			if missing > 0 {
				// We should be able to do this in place, no?
				more := make([]byte, 2*match[1] - len(data))
				count, err := f.ReadAt(more, int64(len(data)))
				if err != nil && err != io.EOF {
					log.Fatal(err)
				}
				if count < missing {
					log.Fatal("couldn't read ", missing,
						" bytes from ", f.Name,
						" at ", len(data))
				}
				data = append(data, more...)
			}
			print(string(data[match[0]:match[1]]), "\n")
		}
	}
}