package storage

import (
	"database/sql"
)

// The realm, as gogobee pushes it.
//
// Three pages ride one snapshot: the world map, the board, and the hall of
// firsts. They are one push rather than three because they are one *question* —
// "what is this place, and what has happened here" — and because every number in
// all three comes off the same scan of the same run history. Splitting them would
// mean three ways for the same fact to be a different number depending on which
// page you were looking at.
//
// Nothing here is an event. The events (a zone_first dispatch, a death) come down
// the dispatch queue like any other fact. This is the standing state of the world,
// which is the only kind of thing a map can honestly draw.

// RealmOccupant is somebody on an expedition in a zone right now. Token is the
// public board token and is EMPTY only in the sense that this row never exists
// for an opted-out player — unlike a siege contributor, presence is dropped
// outright upstream rather than anonymised, so every row here has a name and a
// link.
type RealmOccupant struct {
	Token string `json:"token,omitempty"`
	Name  string `json:"name"`
	Level int    `json:"level,omitempty"`
	Day   int    `json:"day,omitempty"`
}

// RealmZone is one place in the world: what it is, who first got through it, how
// many have since, and who is inside it.
//
// FirstBy with an empty FirstToken is the anonymised case — the zone HAS been
// cleared and the claim stands, but the clearer opted out and gets no name and no
// link. Clears > 0 with no FirstBy at all is the same state seen from the other
// side, and both render as "cleared, by somebody" rather than as never-cleared,
// which would be a false statement about the realm rather than a withheld one.
type RealmZone struct {
	ID         string `json:"id"`
	Display    string `json:"display"`
	Tier       int    `json:"tier"`
	LevelMin   int    `json:"level_min"`
	LevelMax   int    `json:"level_max"`
	Faction    string `json:"faction,omitempty"`
	Atmosphere string `json:"atmosphere,omitempty"`
	Postgame   bool   `json:"postgame,omitempty"`

	FirstClearBy    string `json:"first_clear_by,omitempty"`
	FirstClearToken string `json:"first_clear_token,omitempty"`
	FirstClearAt    int64  `json:"first_clear_at,omitempty"`

	Clears   int `json:"clears"`
	Clearers int `json:"clearers"`

	Occupants []RealmOccupant `json:"occupants,omitempty"`
}

// RealmFirst is one entry in the hall of firsts.
type RealmFirst struct {
	Kind    string `json:"kind"`
	Target  string `json:"target"`
	Display string `json:"display"`
	Tier    int    `json:"tier,omitempty"`
	Holder  string `json:"holder,omitempty"`
	Token   string `json:"token,omitempty"`
	AtUnix  int64  `json:"at_unix"`
}

// RealmStanding is one line on the board.
type RealmStanding struct {
	Token       string `json:"token,omitempty"`
	Name        string `json:"name"`
	Level       int    `json:"level"`
	ClassRace   string `json:"class_race,omitempty"`
	DeepestTier int    `json:"deepest_tier"`
	Clears      int    `json:"clears"`
	Zones       int    `json:"zones"`
	Firsts      int    `json:"firsts"`
	SiegeDamage int    `json:"siege_damage"`
	SiegeFights int    `json:"siege_fights"`
}

// Realm is the whole snapshot.
type Realm struct {
	Zones      []RealmZone     `json:"zones,omitempty"`
	Firsts     []RealmFirst    `json:"firsts,omitempty"`
	Standings  []RealmStanding `json:"standings,omitempty"`
	SnapshotAt int64           `json:"snapshot_at"`
}

// ReplaceRealm swaps the whole realm for a new snapshot, in one transaction.
//
// Replace, never merge, for the reason the siege does it: a zone whose clear
// count was corrected upstream, a player who opted out, an occupant who came
// home — all of those are *removals*, and a merge has no way to express one. The
// transaction means a reader mid-swap sees the old realm or the new one, never a
// zone list with the previous board under it.
func ReplaceRealm(r Realm, snapshotAt int64) error {
	tx, err := Get().Begin()
	if err != nil {
		return err
	}
	defer func() { _ = tx.Rollback() }()

	for _, t := range []string{
		"adventure_realm_zone",
		"adventure_realm_occupant",
		"adventure_realm_first",
		"adventure_realm_standing",
	} {
		if _, err := tx.Exec(`DELETE FROM ` + t); err != nil {
			return err
		}
	}

	zstmt, err := tx.Prepare(`
		INSERT INTO adventure_realm_zone
		    (pos, zone_id, display, tier, level_min, level_max, faction, atmosphere,
		     postgame, first_by, first_token, first_at, clears, clearers)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`)
	if err != nil {
		return err
	}
	defer zstmt.Close()

	ostmt, err := tx.Prepare(`
		INSERT INTO adventure_realm_occupant (pos, zone_id, token, name, level, day)
		VALUES (?, ?, ?, ?, ?, ?)`)
	if err != nil {
		return err
	}
	defer ostmt.Close()

	opos := 0
	for i, z := range r.Zones {
		if _, err := zstmt.Exec(i, z.ID, z.Display, z.Tier, z.LevelMin, z.LevelMax,
			z.Faction, z.Atmosphere, z.Postgame, z.FirstClearBy, z.FirstClearToken,
			z.FirstClearAt, z.Clears, z.Clearers); err != nil {
			return err
		}
		for _, o := range z.Occupants {
			if _, err := ostmt.Exec(opos, z.ID, o.Token, o.Name, o.Level, o.Day); err != nil {
				return err
			}
			opos++
		}
	}

	fstmt, err := tx.Prepare(`
		INSERT INTO adventure_realm_first (pos, kind, target, display, tier, holder, token, at_unix)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`)
	if err != nil {
		return err
	}
	defer fstmt.Close()
	for i, f := range r.Firsts {
		if _, err := fstmt.Exec(i, f.Kind, f.Target, f.Display, f.Tier, f.Holder, f.Token, f.AtUnix); err != nil {
			return err
		}
	}

	sstmt, err := tx.Prepare(`
		INSERT INTO adventure_realm_standing
		    (pos, token, name, level, class_race, deepest_tier, clears, zones, firsts,
		     siege_damage, siege_fights)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`)
	if err != nil {
		return err
	}
	defer sstmt.Close()
	for i, s := range r.Standings {
		if _, err := sstmt.Exec(i, s.Token, s.Name, s.Level, s.ClassRace, s.DeepestTier,
			s.Clears, s.Zones, s.Firsts, s.SiegeDamage, s.SiegeFights); err != nil {
			return err
		}
	}

	if _, err := tx.Exec(`
		INSERT INTO adventure_realm_meta (id, snapshot_at) VALUES (1, ?)
		ON CONFLICT(id) DO UPDATE SET snapshot_at = excluded.snapshot_at`, snapshotAt); err != nil {
		return err
	}
	return tx.Commit()
}

// LoadRealm returns the realm as last pushed. ok is false when gogobee has never
// pushed one — distinct from a pushed snapshot that happens to be empty, which is
// a real answer (a realm with no living adventurers on the board is a thing that
// can be true) and which the pages render differently.
func LoadRealm() (Realm, bool, error) {
	var r Realm
	err := Get().QueryRow(`SELECT snapshot_at FROM adventure_realm_meta WHERE id = 1`).
		Scan(&r.SnapshotAt)
	if err == sql.ErrNoRows {
		return Realm{}, false, nil
	}
	if err != nil {
		return Realm{}, false, err
	}

	// Each cursor is drained fully before the next query opens. The pool is one
	// connection wide, and a nested read is the deadlock the run-beat batch
	// shipped with and then had to have cut out of it.
	zones, err := loadRealmZones()
	if err != nil {
		return r, true, err
	}
	occ, err := loadRealmOccupants()
	if err != nil {
		return r, true, err
	}
	for i := range zones {
		zones[i].Occupants = occ[zones[i].ID]
	}
	r.Zones = zones

	if r.Firsts, err = loadRealmFirsts(); err != nil {
		return r, true, err
	}
	if r.Standings, err = loadRealmStandings(); err != nil {
		return r, true, err
	}
	return r, true, nil
}

func loadRealmZones() ([]RealmZone, error) {
	rows, err := Get().Query(`
		SELECT zone_id, display, tier, level_min, level_max, faction, atmosphere,
		       postgame, first_by, first_token, first_at, clears, clearers
		  FROM adventure_realm_zone ORDER BY pos ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []RealmZone
	for rows.Next() {
		var z RealmZone
		if err := rows.Scan(&z.ID, &z.Display, &z.Tier, &z.LevelMin, &z.LevelMax,
			&z.Faction, &z.Atmosphere, &z.Postgame, &z.FirstClearBy, &z.FirstClearToken,
			&z.FirstClearAt, &z.Clears, &z.Clearers); err != nil {
			return nil, err
		}
		out = append(out, z)
	}
	return out, rows.Err()
}

func loadRealmOccupants() (map[string][]RealmOccupant, error) {
	rows, err := Get().Query(`
		SELECT zone_id, token, name, level, day
		  FROM adventure_realm_occupant ORDER BY pos ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := map[string][]RealmOccupant{}
	for rows.Next() {
		var zoneID string
		var o RealmOccupant
		if err := rows.Scan(&zoneID, &o.Token, &o.Name, &o.Level, &o.Day); err != nil {
			return nil, err
		}
		out[zoneID] = append(out[zoneID], o)
	}
	return out, rows.Err()
}

func loadRealmFirsts() ([]RealmFirst, error) {
	rows, err := Get().Query(`
		SELECT kind, target, display, tier, holder, token, at_unix
		  FROM adventure_realm_first ORDER BY pos ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []RealmFirst
	for rows.Next() {
		var f RealmFirst
		if err := rows.Scan(&f.Kind, &f.Target, &f.Display, &f.Tier, &f.Holder, &f.Token, &f.AtUnix); err != nil {
			return nil, err
		}
		out = append(out, f)
	}
	return out, rows.Err()
}

func loadRealmStandings() ([]RealmStanding, error) {
	rows, err := Get().Query(`
		SELECT token, name, level, class_race, deepest_tier, clears, zones, firsts,
		       siege_damage, siege_fights
		  FROM adventure_realm_standing ORDER BY pos ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []RealmStanding
	for rows.Next() {
		var s RealmStanding
		if err := rows.Scan(&s.Token, &s.Name, &s.Level, &s.ClassRace, &s.DeepestTier,
			&s.Clears, &s.Zones, &s.Firsts, &s.SiegeDamage, &s.SiegeFights); err != nil {
			return nil, err
		}
		out = append(out, s)
	}
	return out, rows.Err()
}

// DeathsBySubject counts the deaths Pete has reported for each named adventurer.
//
// This is the one standings number that does NOT come off the gogobee push, and
// the reason is that the game has nowhere to read it from: a character carries
// its most recent death (source, place, date) and no running total, so there is
// no lifetime count on the game box to send. Pete does have one — his own back
// catalogue of death dispatches, seeded at news launch by the backfill and
// complete since — so he counts them himself, which is a thing a newspaper is
// entitled to do about its own reporting.
//
// Keyed on the character name because that is the only join the fact table
// offers: a dispatch carries a name, never a token. Names are unique per realm in
// practice; a collision would merge two adventurers' death counts, which is why
// this is the only column derived this way and not, say, clears.
func DeathsBySubject() (map[string]int, error) {
	rows, err := Get().Query(`
		SELECT subject, COUNT(*) FROM adventure_events
		 WHERE event_type = 'death' AND subject IS NOT NULL AND subject <> ''
		 GROUP BY subject`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := map[string]int{}
	for rows.Next() {
		var name string
		var n int
		if err := rows.Scan(&name, &n); err != nil {
			return nil, err
		}
		out[name] = n
	}
	return out, rows.Err()
}

// PeteDuelRecord is Pete's own won/lost tally, from the dispatches he filed about
// himself. He is a companion who can be hired onto an expedition and he has a
// record; keeping score on himself is in voice, and it is the one line on the
// board that is not about a player.
//
// Both types have had templates in the renderer since before anything emitted
// them, so this reads zero until gogobee starts filing them — and zero-zero is
// rendered as "no bouts yet" rather than as a 0% win rate.
func PeteDuelRecord() (wins, losses int, err error) {
	err = Get().QueryRow(`
		SELECT
		  COALESCE(SUM(CASE WHEN event_type = 'pete_duel_win'  THEN 1 ELSE 0 END), 0),
		  COALESCE(SUM(CASE WHEN event_type = 'pete_duel_loss' THEN 1 ELSE 0 END), 0)
		FROM adventure_events
		WHERE event_type IN ('pete_duel_win', 'pete_duel_loss')`).Scan(&wins, &losses)
	if err == sql.ErrNoRows {
		return 0, 0, nil
	}
	return wins, losses, err
}