cmd_back.v

1//! Going back: `koh undo`, `koh revert` and `koh load`.2//!3//! Nothing here rewinds history. A going-back command restores an earlier tree4//! and records that as a new save whose `restores` field names the save it5//! brought back, so the move itself can be undone.6//!7//! The order matters and is the same everywhere: show what will change, ask,8//! record the new save, then write the files. Recording before writing means a9//! crash mid-restore shows up in `status` and `revert` finishes it.1011module cli1213import json14import src.fmt15import src.history16import src.snapshot17import src.storage1819pub fn cmd_undo(raw []string) int {20	args := parse('undo', raw, Options{21		flags: ['session', 'yes', 'json']22	}) or { return usage_error(err.msg()) }23	store := open_store() or { return refuse(args.json(), err.msg()) }24	defer {25		store.close()26	}27	effective := history.effective(store) or { return refuse(args.json(), err.msg()) }28	mut target := history.Save{}29	if args.flag('session') {30		start := history.session_start(store, effective.id) or {31			return refuse(args.json(), err.msg())32		}33		if start.parent == '' {34			return refuse(args.json(), 'there is nothing before session "${start.session}"')35		}36		target = history.by_id(store, start.parent) or { return refuse(args.json(), err.msg()) }37	} else {38		mut steps := 139		if args.positional.len > 0 {40			steps = args.positional_at(0).int()41			if steps < 1 {42				return usage_error('undo takes a positive number of saves')43			}44		}45		target = history.step_back(store, effective.id, steps) or {46			return refuse(args.json(), err.msg())47		}48	}49	return going_back(store, target, 'undo', args, false)50}5152pub fn cmd_revert(raw []string) int {53	args := parse('revert', raw, Options{54		flags: ['yes', 'json']55	}) or { return usage_error(err.msg()) }56	store := open_store() or { return refuse(args.json(), err.msg()) }57	defer {58		store.close()59	}60	head := history.head(store) or {61		return refuse(args.json(), 'this repo has no saves yet — nothing to revert to')62	}63	changes := compare_with_head(store, head) or { return refuse(args.json(), err.msg()) }64	if !changes.dirty {65		if args.json() {66			emit_json(json.encode(RevertJson{67				reverted: false68				head_id:  head.id69			}))70			return 071		}72		ok('working tree already matches [${head.id}]')73		return 074	}75	// The state about to be discarded is recorded as a checkpoint, so a revert76	// is itself undoable. `record_discard` does that only after the answer.77	return going_back(store, head, 'revert', args, true)78}7980pub fn cmd_load(raw []string) int {81	args := parse('load', raw, Options{82		flags: ['checkpoint', 'yes', 'json']83	}) or { return usage_error(err.msg()) }84	store := open_store() or { return refuse(args.json(), err.msg()) }85	defer {86		store.close()87	}88	mut target := history.Save{}89	if args.flag('checkpoint') {90		target = history.latest_checkpoint(store) or {91			return refuse(args.json(), 'this repo has no checkpoints')92		}93	} else {94		id := args.positional_at(0)95		if id == '' {96			return usage_error('load needs a save ID, or --checkpoint')97		}98		target = history.resolve(store, id) or { return refuse(args.json(), err.msg()) }99	}100	return going_back(store, target, 'load', args, false)101}102103// going_back is the shared path. `discard_first` is revert's extra step: record104// the changes being thrown away before restoring.105fn going_back(store &storage.Store, target history.Save, verb string, args Args, discard_first bool) int {106	as_json := args.json()107	if as_json && !args.flag('yes') {108		return refuse(true, 'needs --yes when not interactive')109	}110	if !discard_first {111		require_clean(store) or { return refuse(as_json, err.msg()) }112	}113	preview := plan_restore(store, target) or { return refuse(as_json, err.msg()) }114	if !as_json {115		ok('${verb}: [${target.id}]  ${target.message}')116		for delta in preview.deltas {117			println('  ${change_mark(delta.kind)} ${delta.path}')118		}119		note('${fmt.plural(preview.deltas.len, 'file')} change  ·  ${fmt.plural(preview.remove.len,120			'file')} removed')121	}122	approved := confirm(args.flag('yes')) or { return refuse(as_json, err.msg()) }123	if !approved {124		return 1125	}126	// The tree may have changed while the prompt waited, so the restore acts on127	// a fresh plan; the one above only drew the preview.128	if !discard_first {129		require_clean(store) or { return refuse(as_json, err.msg()) }130	}131	plan := plan_restore(store, target) or { return refuse(as_json, err.msg()) }132	save := apply_restore(store, target, verb, plan, discard_first) or {133		return refuse(as_json, err.msg())134	}135	report := snapshot.restore_files(store, store.root, snapshot.load(store.root), plan.files,136		plan.remove) or { return refuse(as_json, err.msg()) }137	if as_json {138		emit_json(json.encode(BackJson{139			id:        save.id140			restores:  target.id141			written:   report.written142			removed:   report.removed143			discarded: discard_first144		}))145		return 0146	}147	ok('restored [${save.id}]  ${save.message}')148	return 0149}150151// apply_restore records the going-back as a new save. It does not touch the152// working tree and does not ask anything: the history view has already asked,153// and the order still has to be save-first, files-second.154pub fn apply_restore(store &storage.Store, target history.Save, verb string, plan RestorePlan, discard_first bool) !history.Save {155	if discard_first {156		history.commit_worktree(store, store.root, snapshot.load(store.root), history.SaveInput{157			message:       'revert: discarded changes'158			is_checkpoint: true159		})!160	}161	return history.commit_files(store, '', plan.files, history.SaveInput{162		message:  '${verb}: ${target.id}'163		restores: target.id164	})!165}166167// restore_now performs a whole restore without prompting: the plan, the save168// and the files. The history view uses it for its `l` key.169pub fn restore_now(store &storage.Store, target history.Save, verb string) !history.Save {170	require_clean(store)!171	plan := plan_restore(store, target)!172	save := apply_restore(store, target, verb, plan, false)!173	snapshot.restore_files(store, store.root, snapshot.load(store.root), plan.files, plan.remove)!174	return save175}176177struct RestorePlan {178	files  []snapshot.FileEntry179	remove []string180	deltas []snapshot.Delta181}182183const unsaved_changes = 'unsaved changes — save or checkpoint first, or discard them with koh revert'184185// require_clean refuses to restore over work only the disk has, as Koh 2 did.186// `revert` is the one going-back that may discard it, and it records it first.187fn require_clean(store &storage.Store) ! {188	head := history.head(store) or { return }189	if compare_with_head(store, head)!.dirty {190		return error(unsaved_changes)191	}192}193194// plan_restore works out what writing `target` back onto disk involves. Every195// file on disk the target lacks goes: undo, load and pluck only run on a clean196// tree, so those are tracked files, and revert has recorded the rest.197fn plan_restore(store &storage.Store, target history.Save) !RestorePlan {198	files := history.files_of(store, target.id)!199	mut wanted := map[string]bool{}200	for file in files {201		wanted[file.path] = true202	}203	from := working_tree(store)!204	mut remove := []string{}205	for file in from.files {206		if file.path !in wanted {207			remove << file.path208		}209	}210	deltas := snapshot.diff_trees(store, from, snapshot.Tree{211		files: files212	})!213	return RestorePlan{214		files:  files215		remove: remove216		deltas: deltas217	}218}219220fn change_mark(kind string) string {221	if kind == 'added' {222		return green('+')223	}224	if kind == 'removed' {225		return red('-')226	}227	return amber('~')228}229230struct BackJson {231	id        string232	restores  string233	written   int234	removed   int235	discarded bool236}237238struct RevertJson {239	reverted bool240	head_id  string241}