#!/usr/bin/c++script
// Present files ordered by size.
// Even if the recurse option is used, the files are not presented by
// directory, but a flat views shows all the files ordered by size
#include <algorithm>

string formatnum (size_t num, bool human)
{
	if (num < 1000){
		return format ("{}",num);
	}else if (human){
		string_view suffix = "";
		size_t fraction = 0; 
		pair<unsigned,string_view> tblimit[]={
			{1000*1000*1000*1000u,"T"},{1000*1000*1000u,"G"},{1000*1000u,"M"},{1000u,"K"}
		};
		for (auto limit:tblimit){
			if (num > limit.first){
				fraction = (num % limit.first)/(limit.first/10.0)+0.5;
				num /= limit.first;
				if (fraction == 10){
					fraction = 0;
					num++;
				}
				suffix = limit.second;
				break;
			}
		}
		return format ("{}.{}{}",num,fraction,suffix);
	}else{
		// Insert , in long numbers. First turn num into string
		string tmp = format ("{}",num);
		string ret;
		// reverse tmp and seperate in chunks of 3 numbers.
		// put the range in it original order, but the content is itself reversed
		for (auto &&r:tmp|views::reverse|views::chunk(3)|views::reverse
			| views::transform([](auto &&s){return s|views::reverse;})
			| views::join_with(","sv)){
			ret += r;
		}
		return ret;		
	}
}
#main
progdesc("Search large files on disk");
option<string> dirscan('d',"directory","Directory to scan",".",false);
option<bool> human ('h',"human-readable","Present file size with suffix",false,false);
option<bool> recurse('r',"recurse","Search sub-directory",false,false);
option<bool> reverse('R',"reverse","Show largest files first",false,false);

struct RESULT{
	string dirname;
	string name;
	size_t size;
};
vector<RESULT> results;
vector<string> dirs{dirscan.val};
while (dirs.size() > 0){
	DIRNAME dir(dirs[0]);
	dirs.erase(dirs.begin());
	for (auto &&st:dir.ls()
		| DIRNAME::drop_dot_dirs()
		| DIRNAME::stat()){
		if (st.is_dir()){
			//cout << format ("Dir  {}/{}\n",st.dirname,st.name);
			if (recurse.val) dirs.push_back(format("{}/{}",st.dirname,st.name));
		}else if (st.is_reg()){
			//cout << format ("file {}/{}, mode {}, size {}\n",st.dirname,st.name,st.mode,st.size);
			results.emplace_back(st.dirname,st.name,st.size);
		}
	}
}
if (reverse.val){
	ranges::sort(results,std::greater{},&RESULT::size);
}else{
	ranges::sort(results,std::less{},&RESULT::size);
}
for (auto &r:results) cout << format ("{:>15}  {}/{}\n",formatnum(r.size,human.val),r.dirname,r.name);