package vocab

import (
	"database/sql"
	"strings"
	"unicode"
)

// Planting: the garden's second source.
//
// Capture (handlers.go) records words the writer *sought out*. Planting records
// phrasing she was gently *given* — an accepted collocation like "make a
// decision" is a learnable chunk exactly like a looked-up word, and the SM-2-lite
// scheduler doesn't care that it's three words rather than one. Together the two
// halves make the garden a record of both sides of learning.
//
// Everything here is best-effort by design: planting hangs off accepting a
// suggestion, and that accept must succeed whether or not a card comes of it.

// Execer is the slice of *sql.DB (or *sql.Tx) that planting needs.
type Execer interface {
	Exec(query string, args ...any) (sql.Result, error)
}

// Phrase is one chunk to plant.
type Phrase struct {
	Text    string  // the corrected phrasing, e.g. "make a decision"
	Meaning string  // why it's better — the suggestion's explanation
	Example string  // the sentence she met it in, already corrected
	DocID   *string // where, so "where did I see this?" stays one tap
	// Lang is the document's verdict ('' | 'en' | 'pair'), because the chunk is
	// lifted out of her own prose and is therefore in whatever language that
	// prose is. See migration 0018.
	Lang string
}

// Phrase-card caps. A collocation is a short chunk; anything longer is a
// rewritten sentence wearing a collocation's label, and a sentence makes a
// miserable flashcard. Both bounds are deliberately tight — the cost of
// skipping a real chunk is one missing card, the cost of planting a sentence is
// a garden the writer stops trusting.
const (
	maxPhraseRunes = 60
	maxPhraseWords = 6
	minPhraseWords = 2
)

// PhraseKey normalizes a replacement into a garden key, or returns "" when the
// text isn't a plantable chunk.
//
// Lowercasing matches capture's normalization, so a phrase and a looked-up word
// share one UNIQUE(user_id, word) namespace rather than colliding sideways.
// Single words are rejected on purpose: a one-word fix is word choice, and word
// choice already reaches the garden through lookup — planting it here would give
// it a card with no gloss and no phonetic, which reviews badly.
func PhraseKey(text string) string {
	// Collapse all whitespace (a replacement can carry a newline from the
	// editor) so the key is stable and the word count is honest.
	s := strings.Join(strings.Fields(strings.ToLower(text)), " ")
	// Trim the punctuation a phrase picks up from the sentence around it, but
	// leave inner marks alone: "can't afford" and "in one's own time" are chunks.
	s = strings.Trim(s, `.,;:!?…"'“”‘’()[]`)
	s = strings.TrimSpace(s)
	if s == "" || len([]rune(s)) > maxPhraseRunes {
		return ""
	}
	n := len(strings.Fields(s))
	if n < minPhraseWords || n > maxPhraseWords {
		return ""
	}
	// A chunk of pure digits or symbols ("12 000", "-- --") isn't vocabulary.
	if !strings.ContainsFunc(s, unicode.IsLetter) {
		return ""
	}
	return s
}

// Plant adds a phrase card to the garden, due tomorrow like any fresh capture.
// It reports whether a new card was created.
//
// ON CONFLICT DO NOTHING, unlike capture's refresh-the-context upsert: accepting
// the same collocation again months later is evidence the chunk is still being
// learned, and the last thing that should do is overwrite the card's first
// context or disturb a schedule it has been climbing. An existing card wins.
func Plant(ex Execer, userID string, p Phrase) (bool, error) {
	key := PhraseKey(p.Text)
	if key == "" {
		return false, nil
	}
	res, err := ex.Exec(
		`INSERT INTO vocab_words (user_id, word, gloss, definition, phonetic, example, doc_id, lang, due_at, interval_days)
		 VALUES (?, ?, '', ?, '', ?, ?, ?, datetime('now', '+1 day'), 1)
		 ON CONFLICT(user_id, word) DO NOTHING`,
		userID, key,
		clamp(strings.TrimSpace(p.Meaning), maxDefinitionLen),
		clamp(strings.TrimSpace(p.Example), maxExampleLen),
		p.DocID,
		p.Lang,
	)
	if err != nil {
		return false, err
	}
	n, err := res.RowsAffected()
	return n > 0, err
}