package storage

import (
	"database/sql"
)

// The expedition liveblog, as gogobee beats it out room by room.
//
// Everything else the game pushes is a snapshot: the board, the war room, a
// player's own sheet. Those get replaced whole, because they describe what is
// currently true. Beats are the opposite kind of thing — each one is a moment
// that happened, and the only correction a later push can make to a moment is to
// add another one after it. So this is append-only, keyed on (run_id, seq), and
// a re-sent batch collapses on the primary key instead of duplicating a story.
//
// The run header is *derived*, not pushed. gogobee sends beats and nothing else;
// AppendRunBeats folds the identifying ones into adventure_run as they arrive.
// The upside is that a run missing its `start` beat still has a log — anonymous,
// but readable — rather than being discarded for want of a name to hang it on.

// RunBeat is one moment inside a run, exactly as gogobee filed it. Nouns and
// numbers only: Pete writes the sentence, the same split every dispatch fact
// already respects.
type RunBeat struct {
	RunID      string `json:"run_id"`
	Seq        int64  `json:"seq"`
	Kind       string `json:"kind"`
	OccurredAt int64  `json:"occurred_at"`

	Token      string `json:"token,omitempty"`
	Name       string `json:"name,omitempty"`
	Level      int    `json:"level,omitempty"`
	Zone       string `json:"zone,omitempty"`
	Region     string `json:"region,omitempty"`
	Room       int    `json:"room,omitempty"`
	TotalRooms int    `json:"total_rooms,omitempty"`
	RoomKind   string `json:"room_kind,omitempty"`
	Target     string `json:"target,omitempty"`
	Outcome    string `json:"outcome,omitempty"`
	Amount     int    `json:"amount,omitempty"`
	Count      int    `json:"count,omitempty"`
	HP         int    `json:"hp,omitempty"`
	HPMax      int    `json:"hp_max,omitempty"`
	Crits      int    `json:"crits,omitempty"`
	Fumbles    int    `json:"fumbles,omitempty"`

	// Prose is the single exception to "nouns and numbers only", and it is
	// deliberately confined to one beat kind ("summary"). gogobee's LLM reads the
	// finished run back and says what it was about; Pete guards that text at
	// ingest exactly as it guards a dispatch lede, then folds it onto the run
	// header. It is never rendered as a log line — see renderRunBeat.
	Prose string `json:"prose,omitempty"`
}

// Run is the header: who walked, where, and how it ended (if it has).
type Run struct {
	RunID      string
	Token      string
	Name       string
	Level      int
	Zone       string
	TotalRooms int
	StartedAt  int64
	UpdatedAt  int64
	EndedAt    int64 // 0 = still walking
	Outcome    string
	Summary    string // LLM run summary, empty until the summary beat lands (or forever)
}

// Live reports whether this run is still in progress.
func (r Run) Live() bool { return r.EndedAt == 0 }

// AppendRunBeats stores a batch and folds each beat into its run header, in one
// transaction so a reader never sees a header that has moved ahead of its beats.
//
// INSERT OR IGNORE, not upsert: a beat is immutable. If gogobee re-sends
// (run_id, seq) the stored copy wins, which makes a duplicated batch free and
// makes a *changed* beat impossible — the second is a bug upstream, and quietly
// rewriting history to match it would hide that.
func AppendRunBeats(beats []RunBeat) error {
	if len(beats) == 0 {
		return nil
	}
	tx, err := Get().Begin()
	if err != nil {
		return err
	}
	defer func() { _ = tx.Rollback() }()

	bstmt, err := tx.Prepare(`
		INSERT OR IGNORE INTO adventure_run_beat
		    (run_id, seq, kind, occurred_at, room, total_rooms, room_kind,
		     target, outcome, amount, qty, hp, hp_max, crits, fumbles, region, prose)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`)
	if err != nil {
		return err
	}
	defer bstmt.Close()

	// The header is created by whichever beat arrives first and enriched by any
	// later one that knows more. COALESCE(NULLIF(...)) is the whole trick: a beat
	// that doesn't carry a field leaves the stored value alone, so the `start`
	// beat's name and zone survive the forty beats after it that have neither.
	hstmt, err := tx.Prepare(`
		INSERT INTO adventure_run
		    (run_id, token, name, level, zone, total_rooms, started_at, updated_at, ended_at, outcome, summary)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
		ON CONFLICT(run_id) DO UPDATE SET
		    token       = COALESCE(NULLIF(excluded.token, ''), adventure_run.token),
		    name        = COALESCE(NULLIF(excluded.name, ''), adventure_run.name),
		    level       = COALESCE(NULLIF(excluded.level, 0), adventure_run.level),
		    zone        = COALESCE(NULLIF(excluded.zone, ''), adventure_run.zone),
		    total_rooms = COALESCE(NULLIF(excluded.total_rooms, 0), adventure_run.total_rooms),
		    started_at  = COALESCE(NULLIF(adventure_run.started_at, 0), excluded.started_at),
		    updated_at  = MAX(adventure_run.updated_at, excluded.updated_at),
		    ended_at    = COALESCE(NULLIF(adventure_run.ended_at, 0), excluded.ended_at),
		    outcome     = COALESCE(NULLIF(adventure_run.outcome, ''), excluded.outcome),
		    summary     = COALESCE(NULLIF(adventure_run.summary, ''), excluded.summary)`)
	if err != nil {
		return err
	}
	defer hstmt.Close()

	for _, b := range beats {
		if b.RunID == "" {
			continue
		}
		if _, err := bstmt.Exec(b.RunID, b.Seq, b.Kind, b.OccurredAt, b.Room, b.TotalRooms,
			b.RoomKind, b.Target, b.Outcome, b.Amount, b.Count, b.HP, b.HPMax,
			b.Crits, b.Fumbles, b.Region, b.Prose); err != nil {
			return err
		}

		// A run ends once. First close wins here for the same reason it does on
		// the game side: the specific outcome ("died") is filed before the generic
		// one ("abandoned") that follows it down the same drain.
		var endedAt int64
		var outcome string
		if b.Kind == "end" {
			endedAt = b.OccurredAt
			outcome = b.Outcome
		}
		started := int64(0)
		if b.Kind == "start" {
			started = b.OccurredAt
		}
		// Only the summary beat may set the summary. Any other kind carrying prose
		// is upstream noise, and letting it through would put unguarded text on the
		// header — the guard at ingest only inspects the kind it knows about.
		summary := ""
		if b.Kind == "summary" {
			summary = b.Prose
		}
		if _, err := hstmt.Exec(b.RunID, b.Token, b.Name, b.Level, b.Zone,
			b.TotalRooms, started, b.OccurredAt, endedAt, outcome, summary); err != nil {
			return err
		}
	}
	return tx.Commit()
}

// LatestRunForToken returns the run worth showing on one adventurer's page.
//
// A LIVE run always wins, and only then does recency decide. That ordering is
// load-bearing at exactly one moment and it is a moment that happens on every
// multi-region expedition: crossing a border closes one run and opens the next
// in the same breath, so the outgoing run's `end` beat and the incoming run's
// `start` beat carry the same second. Ordering on the clock alone would leave
// the page showing the log of a region the party has already left, with a
// "cleared" chip on it, while they walk on in the next one.
//
// Recency is updated_at rather than started_at for the same reason: the run
// still moving is the one still being written to.
func LatestRunForToken(token string) (Run, bool, error) {
	if token == "" {
		return Run{}, false, nil
	}
	var r Run
	err := Get().QueryRow(`
		SELECT run_id, token, name, level, zone, total_rooms,
		       started_at, updated_at, ended_at, outcome, summary
		  FROM adventure_run
		 WHERE token = ?
		 ORDER BY (ended_at = 0) DESC, updated_at DESC, started_at DESC
		 LIMIT 1`, token).Scan(
		&r.RunID, &r.Token, &r.Name, &r.Level, &r.Zone, &r.TotalRooms,
		&r.StartedAt, &r.UpdatedAt, &r.EndedAt, &r.Outcome, &r.Summary)
	if err == sql.ErrNoRows {
		return Run{}, false, nil
	}
	if err != nil {
		return Run{}, false, err
	}
	return r, true, nil
}

// RunByID returns one run header.
func RunByID(runID string) (Run, bool, error) {
	var r Run
	err := Get().QueryRow(`
		SELECT run_id, token, name, level, zone, total_rooms,
		       started_at, updated_at, ended_at, outcome, summary
		  FROM adventure_run WHERE run_id = ?`, runID).Scan(
		&r.RunID, &r.Token, &r.Name, &r.Level, &r.Zone, &r.TotalRooms,
		&r.StartedAt, &r.UpdatedAt, &r.EndedAt, &r.Outcome, &r.Summary)
	if err == sql.ErrNoRows {
		return Run{}, false, nil
	}
	if err != nil {
		return Run{}, false, err
	}
	return r, true, nil
}

// RunBeats returns a run's beats in the order they happened.
//
// limit caps from the END, not the start: a log is read for what just happened,
// and a run deep into its third region would otherwise show its first forty
// beats forever. The returned slice is still oldest-first.
func RunBeats(runID string, limit int) ([]RunBeat, error) {
	if runID == "" {
		return nil, nil
	}
	q := `SELECT run_id, seq, kind, occurred_at, room, total_rooms, room_kind,
	             target, outcome, amount, qty, hp, hp_max, crits, fumbles, region, prose
	        FROM adventure_run_beat WHERE run_id = ? ORDER BY seq ASC`
	args := []any{runID}
	if limit > 0 {
		// Innermost query takes the tail, the wrapper puts it back in order.
		q = `SELECT * FROM (
		         SELECT run_id, seq, kind, occurred_at, room, total_rooms, room_kind,
		                target, outcome, amount, qty, hp, hp_max, crits, fumbles, region, prose
		           FROM adventure_run_beat WHERE run_id = ? ORDER BY seq DESC LIMIT ?
		     ) ORDER BY seq ASC`
		args = append(args, limit)
	}
	rows, err := Get().Query(q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []RunBeat
	for rows.Next() {
		var b RunBeat
		if err := rows.Scan(&b.RunID, &b.Seq, &b.Kind, &b.OccurredAt, &b.Room, &b.TotalRooms,
			&b.RoomKind, &b.Target, &b.Outcome, &b.Amount, &b.Count, &b.HP, &b.HPMax,
			&b.Crits, &b.Fumbles, &b.Region, &b.Prose); err != nil {
			return nil, err
		}
		out = append(out, b)
	}
	return out, rows.Err()
}

// PruneRuns drops runs (and their beats) that ended before cutoff. Live runs are
// never touched however old they look — a run that has been walking for a week
// is a stuck expedition, and deleting its log is exactly the wrong response to
// the one case where somebody wants to read it.
func PruneRuns(cutoff int64) error {
	if _, err := Get().Exec(`
		DELETE FROM adventure_run_beat
		 WHERE run_id IN (SELECT run_id FROM adventure_run WHERE ended_at > 0 AND ended_at < ?)`,
		cutoff); err != nil {
		return err
	}
	_, err := Get().Exec(`DELETE FROM adventure_run WHERE ended_at > 0 AND ended_at < ?`, cutoff)
	return err
}