//! `koh update` — put a newer published koh in place of this one (§12).
//!
//! Nothing is installed without being asked, and nothing is removed: the new
//! binary replaces the running one by rename, which is the step that makes the
//! change visible.

module cli

import json2
import src.build
import src.update

pub fn cmd_update(raw []string) int {
	args := parse('update', raw, Options{
		flags: ['check', 'json', 'yes']
	}) or { return usage_error(err.msg()) }
	if args.positional.len > 0 {
		return usage_error('update takes no arguments, not "${args.positional_at(0)}"')
	}
	if args.json() && !args.flag('yes') && !args.flag('check') {
		// The question cannot be asked inside a JSON document, so an install asked
		// for in JSON has to be asked for with --yes as well. That is a mistake in
		// the command line, not a refusal of the work.
		return usage_error('--json needs --yes when it would install')
	}
	current := version
	platform := build.this_machine() or { return refuse(args.json(), err.msg()) }
	checked := update.check(current, platform) or { return refuse(args.json(), err.msg()) }
	latest := if checked.update {
		checked.available
	} else {
		if args.json() {
			emit_json(json2.encode(UpdateJson{
				current:   current
				latest:    current
				available: false
			}))
		} else {
			ok('koh ${current} is the newest — nothing to do')
		}
		return 0
	}
	if args.flag('check') {
		if args.json() {
			emit_json(json2.encode(UpdateJson{
				current:   current
				latest:    latest.version
				available: true
				notes:     latest.notes
			}))
		} else {
			ok('koh ${latest.version} is available — you have ${current}')
			if latest.notes != '' {
				note(latest.notes)
			}
			note('run "koh update" to install it')
		}
		// `--check` reports and says so with its exit code, so a script can ask.
		return 1
	}
	if !args.json() {
		note('${current} → ${latest.version}')
		if latest.notes != '' {
			note(latest.notes)
		}
	}
	// A "no" at the question is a refusal, not a reason to carry on.
	approved := confirm(args.flag('yes')) or { return refuse(args.json(), err.msg()) }
	if !approved {
		return refuse(args.json(), 'not updating, then')
	}
	target := update.install(latest) or { return refuse(args.json(), err.msg()) }
	if args.json() {
		emit_json(json2.encode(UpdateJson{
			current:   current
			latest:    latest.version
			available: true
			installed: target
		}))
		return 0
	}
	ok('installed koh ${latest.version} as ${target}')
	return 0
}

struct UpdateJson {
	current   string
	latest    string
	available bool
	installed string
	notes     string
}