package router

import (
	"regexp"
	"strings"

	"github.com/kami/maven/internal/lexicon"
	"github.com/kami/maven/internal/morph"
	"github.com/kami/maven/internal/store"
)

// A spoken status change over the task list (Vikunja #512, step 4 of
// docs/plans/15-board-surface.md).
//
// Capture and the list read were built; moving a task was only possible in the
// two turns after she read one out, through resolveCandidate — "первую сделал"
// against the bound list. Naming the task instead of its position reached
// nothing: "закрой задачу купить молоко" routed act, found no allowlisted fn,
// and the gate asked "Что сделать?".
//
// Same shape TaskCaptureGrammar uses, for the same reason: no eighth intent, so
// the grammar matches broadly and a deterministic parser inside Build decides.
// The task's own warning applies — every such grammar runs its parser ahead of
// the resident model on every turn, so this is the last one that is free.
//
// TaskStatusFn is the fn slot the daemon dispatches on. Not a Hexis capability
// and not a Praxis one: the board is Maven's own store, so actionAct intercepts
// this name before either ecosystem client sees it.
const TaskStatusFn = "task_status"

// TaskStatus — a parsed status change. Status is a store task status, and Text
// is the task he named, empty when he named none ("закрой задачу"), which is a
// turn the daemon claims and answers by asking which.
type TaskStatus struct {
	Status string
	Text   string
}

// taskStatusNouns — the noun that makes this a board turn rather than ordinary
// speech. Required, and it is the whole reason this rule is safe to run on every
// utterance: "готово" alone is him reporting his day, "убери" alone is a request
// about the room, and neither names the list.
//
// "дело" is deliberately absent. "в чём дело" and "дело в том" are ordinary
// speech, and "список дел" is already a list query.
var taskStatusNouns = []string{"task", "tasks", "todo", "todos"}

// taskStatusFillers — the words to ignore when what is left over is the task he
// named. Prepositions and the possessive, because "убери из моих задач купить
// молоко" names the same task as "убери задачу купить молоко".
var taskStatusFillers = []string{"из", "в", "во", "с", "со", "мои", "моих", "моё", "мой", "моя", "мою", "my", "the", "from", "off", "as", "как"}

// ParseTaskStatus reads a status change over the board: which transition, and
// which task.
//
// Three conditions, all required. A task noun, so no ordinary sentence claims
// the turn. Exactly one status class, because "готово, убери" names two and
// asking beats picking. And a status word that is either an imperative in the
// exact form he said it or a stative by lemma — the trap quiet_toggle.go
// documents, where "закрой" and "закрыл" are one lemma and only one is a
// command.
func ParseTaskStatus(text string) (TaskStatus, bool) {
	toks := praxisTokens(strings.ToLower(strings.TrimSpace(text)))
	if len(toks) == 0 || !taskStatusNamesBoard(toks) {
		return TaskStatus{}, false
	}
	status := ""
	for _, c := range []struct {
		status string
		words  []string
	}{
		{store.TaskDone, lexicon.TaskDoneWords()},
		{store.TaskDropped, lexicon.TaskDropWords()},
	} {
		if !taskStatusHasWord(toks, c.words) {
			continue
		}
		if status != "" {
			// Two transitions in one sentence. They are different rows on the
			// page, so this declines and the cascade answers.
			return TaskStatus{}, false
		}
		status = c.status
	}
	if status == "" {
		return TaskStatus{}, false
	}
	return TaskStatus{Status: status, Text: taskStatusReferent(toks)}, true
}

// taskStatusNamesBoard reports whether the sentence names the task list. The
// Russian noun is matched by lemma, because a noun means the same thing in every
// case and he says "из задач", "задачу", "задача" for one list.
func taskStatusNamesBoard(toks []string) bool {
	for _, t := range toks {
		if morph.SameWord(t, "задача") {
			return true
		}
		for _, n := range taskStatusNouns {
			if t == n {
				return true
			}
		}
	}
	return false
}

// taskStatusHasWord matches a status word the way its set's note requires: an
// imperative exactly, a stative by lemma. It cannot tell the two columns apart
// from the data, so it tries the exact form first and then the lemma — which
// costs the imperative trap back, except that both columns of one set mean the
// SAME transition. "закрой" and "закрыл" are one lemma and, here, one status.
func taskStatusHasWord(toks, words []string) bool {
	for _, t := range toks {
		for _, w := range words {
			if t == w || morph.SameWord(t, w) {
				return true
			}
		}
	}
	return false
}

// taskStatusReferent is what is left after the status words, the board noun and
// the fillers: the task he named, or "" when he named none.
//
// Word order is kept, because the leftover is matched against stored task text
// and he says the task the way he first said it.
func taskStatusReferent(toks []string) string {
	done, drop := lexicon.TaskDoneWords(), lexicon.TaskDropWords()
	var out []string
	for _, t := range toks {
		switch {
		case taskStatusHasWord([]string{t}, done), taskStatusHasWord([]string{t}, drop):
		case morph.SameWord(t, "задача"), taskStatusIn(t, taskStatusNouns):
		case taskStatusIn(t, taskStatusFillers), lexicon.IsFillerParticle(t):
		default:
			out = append(out, t)
		}
	}
	return strings.Join(out, " ")
}

func taskStatusIn(tok string, words []string) bool {
	for _, w := range words {
		if tok == w {
			return true
		}
	}
	return false
}

// TaskStatusGrammar — stage 0 for a spoken status change. Wired after the Praxis
// rules and before the capture marker: Praxis claims a bare "закрой" and this
// rule requires the board noun, so the two cannot collide, and the capture
// marker must not read "убери из задач купить молоко" as a new task.
func TaskStatusGrammar() Grammar {
	return Grammar{
		Name:    "task-status",
		Pattern: regexp.MustCompile(`(?s)^\s*(.+)$`),
		Build: func(m []string) (Decision, bool) {
			c, ok := ParseTaskStatus(m[1])
			if !ok {
				return Decision{}, false
			}
			return Decision{
				Stage:      0,
				Intent:     IntentAct,
				Confidence: 1.0,
				// Value carries the transition and Text the task he named,
				// which is the pairing handlePraxisAct uses for an item and its
				// reference. Empty Text is a claim, not a refusal: the daemon
				// asks which task, having the list she does not.
				Slots: Slots{Fn: TaskStatusFn, HasFn: true, Value: c.Status, Text: c.Text},
			}, true
		},
	}
}