gistfile1.txt

use sys
use std

// XXX move to stdlib
const rename = {from, to
	var ret = sys.rename(from, to)
	-> ret == 0
	
}

const readhist = {histfile
	var tmp
	
	if !std.fexists(histfile)
		tmp = std.sldup(histfile)
		tmp = std.sljoin(&tmp, ".tmp")
		if !std.fexists(tmp)
			std.fatal("history file {} not found\n", histfile)
		;;
		if !rename(tmp, histfile)
			std.fatal("could not rename temporary history file {}\n", tmp)
		;;
		std.slfree(tmp)
	;;
	
	match std.slurp(histfile)
	| `std.Ok commit:
		-> commit
	| `std.Fail err: std.fatal("error reading {}: {}\n", histfile, err)
	;;
}

const updatehist = {histfile, commit
	var tmp
	
	tmp = std.sldup(histfile)
	tmp = std.sljoin(&tmp, ".tmp")
	if !std.blat(tmp, commit, 0o644)
		std.fatal("could not write temporary history file\n")
	;;
	if !std.remove(histfile)
		std.fatal("could not remove old history file\n")
	;;
	if !rename(tmp, histfile)
		std.fatal("could not update history file\n")
	;;
	std.slfree(tmp)
}

const pollrepo = {repo, branch, lastcommit
	var commits = [][:]
	std.slpush(&commits, std.sldup("FAKECOMMIT1"))
	std.slpush(&commits, std.sldup("FAKECOMMIT2"))
	-> commits
}

const runexecscript = {script, repo, hash
	std.put("{} {} {}\n", script, repo, hash)
	-> (0, "FAKEOUTPUT")
}

const runnotifyscript = {script, success, log
	std.put("{} {} <<EOF\n{}\nEOF\n", script, success, log)
}

const run = {repo, histfile, exec, notify
	var lastcommit
	var newcommits
	var success, log

	lastcommit = readhist(histfile)
	newcommits = pollrepo(repo, "master", lastcommit)
	for newcommit in newcommits
		(success, log) = runexecscript(exec, repo, newcommit)
		runnotifyscript(notify, success, log)
		updatehist(histfile, newcommit)
		std.slfree(newcommit)
	;;
	std.slfree(newcommits)
	std.slfree(lastcommit)
}

const main = {args : byte[:][:]
	var cmd
	var repo = ""
	var histfile = ""
	var notify = ""
	var exec = ""
	
	cmd = std.optparse(args, &[
		.opts = [
		    [.opt='r', .arg="repo", .desc="path to repository to monitor", .optional=false],
		    [.opt='f', .arg="history", .desc="path to history file which stores the last commit", .optional=false],
		    [.opt='n', .arg="notify", .desc="path to notify script", .optional=false],
		    [.opt='e', .arg="exec", .desc="path to exec script", .optional=false],
        ][:]
	])
	
	for opt in cmd.opts
		match opt
		| ('r', r): repo = r
		| ('f', f): histfile = f
		| ('n', n): notify = n
		| ('e', e): exec = e
		| _: std.fatal("bad opt\n")
		;;
    ;;
    
    match (repo, histfile, notify, exec)
    | ("", _, _, _): std.fatal("please specify the repo\n")
    | (_, "", _, _): std.fatal("please specify the history file\n")
    | (_, _, "", _): std.fatal("please specify the notify script\n")
    | (_, _, _, ""): std.fatal("please specify the exec script\n")
    | _:
    ;;
    
	run(repo, histfile, exec, notify)
}