#!/usr/bin/env -S v -raw-vsh-tmp-prefix tmp

module main

import os
import log

fn write_chunk(n int, min_size int, original string, start int, end int) {
    size := end - start
    if size < min_size {
        return
    }
    frame_file := 'frame_${n:06}.bin'
    log.warn('writing ${frame_file}, from start: ${start:9}, to end: ${end:9} | size: ${size:9} >= ${min_size:9}, memuse: ${gc_memory_use()}')
    os.write_file(frame_file, original#[start..end]) or { log.error(err.str()) }
}

fn main() {
    log.info('Start.')
    fpath := os.args[2] or { 'memdump.bin' }
    separator := os.args[3] or { '@@ gg_memory_trace_frame' }
    min_size := os.args[1] or { '${separator.len}' }.int()
    log.info('Splitting chunk min_size (arg 1): ${min_size}, file (arg 2): ${fpath}, by string separator (arg 3): `${separator}` ...')
    log.info('Memory use before reading: ${gc_memory_use()}')
    original := os.read_file(fpath)!
    log.info('file size: ${original.len}')
    log.info('Memory use after reading: ${gc_memory_use()}')
    mut n := 0
    for start := 0; start < original.len; {
        gc_collect()
        idx :=
            original.index_after_(separator, start + separator.len) // ensure that we advance each time
        if idx < 0 {
            write_chunk(n, min_size, original, start, original.len)
            break
        }
        write_chunk(n, min_size, original, start, idx)
        start = idx
        n++
    }
    log.info('Memory use after processing: ${gc_memory_use()}')
    log.info('Done.')
}