package app

import (
	"encoding/hex"
	"errors"
	"io/fs"
	"os"
	"strings"
)

func (a *App) recover() error {
	// No other process owns this data directory. Partial sessions are never published.
	// An interrupted attempt may have transferred bytes not yet recorded; charge its full allocation conservatively.
	if _, e := a.db.Exec("UPDATE files SET received=max(received,charged) WHERE status='pending' AND attempts>0 AND parcel IN(SELECT id FROM parcels WHERE state='uploading')"); e != nil {
		return e
	}
	if _, e := a.db.Exec("UPDATE parcels SET state='revoked',version=version+1 WHERE state='uploading'"); e != nil {
		return e
	}
	entries, e := fs.ReadDir(a.root.FS(), "tmp")
	if e != nil {
		return e
	}
	for _, entry := range entries {
		if entry.Type()&os.ModeSymlink != 0 {
			return errors.New("临时目录存在符号链接")
		}
		if e = a.root.RemoveAll("tmp/" + entry.Name()); e != nil {
			return e
		}
	}
	rows, e := a.db.Query("SELECT id FROM objects")
	if e != nil {
		return e
	}
	known := map[string]bool{}
	for rows.Next() {
		var id string
		if e = rows.Scan(&id); e != nil {
			rows.Close()
			return e
		}
		known[id] = true
	}
	e = rows.Err()
	rows.Close()
	if e != nil {
		return e
	}
	for id := range known {
		if len(id) != 32 {
			return errors.New("非法对象标识")
		}
		if _, e := hex.DecodeString(id); e != nil {
			return errors.New("非法对象标识")
		}
		st, e := a.root.Lstat(objectPath(id))
		if e != nil || !st.Mode().IsRegular() {
			if e != nil && !errors.Is(e, os.ErrNotExist) {
				return e
			}
			if _, e = a.db.Exec("UPDATE files SET status='missing' WHERE object_id=?", id); e != nil {
				return e
			}
		}
	}
	e = fs.WalkDir(a.root.FS(), "objects", func(path string, d fs.DirEntry, e error) error {
		if e != nil {
			return e
		}
		if d.Type()&os.ModeSymlink != 0 {
			return errors.New("对象目录存在符号链接")
		}
		if d.IsDir() {
			return nil
		}
		if !known[d.Name()] {
			return a.root.Rename(path, "quarantine/"+randomID())
		}
		return nil
	})
	if e != nil {
		return e
	}
	return a.Cleanup()
}
func (a *App) settleUsage(parcel string) error {
	var ip, visitor, day string
	if e := a.db.QueryRow("SELECT ip,visitor,usage_day FROM parcels WHERE id=?", parcel).Scan(&ip, &visitor, &day); e != nil {
		return e
	}
	var refund int64
	if e := a.db.QueryRow("SELECT COALESCE(sum(max(charged-received,0)),0) FROM files WHERE parcel=?", parcel).Scan(&refund); e != nil {
		return e
	}
	tx, e := a.db.Begin()
	if e != nil {
		return e
	}
	defer tx.Rollback()
	for _, s := range []string{"ip:" + a.keyed(ip), "visitor:" + visitor} {
		if _, e = tx.Exec("UPDATE usage SET bytes=max(0,bytes-?) WHERE subject=? AND day=?", refund, s, day); e != nil {
			return e
		}
	}
	if _, e = tx.Exec("UPDATE files SET charged=received WHERE parcel=?", parcel); e != nil {
		return e
	}
	return tx.Commit()
}
func (a *App) Cleanup() error {
	a.mu.Lock()
	defer a.mu.Unlock()
	now := a.now().Unix()
	rows, e := a.db.Query("SELECT id,state,upload_expires FROM parcels WHERE state='uploading' OR state IN('revoked','expired','exhausted')")
	if e != nil {
		return e
	}
	type parcel struct {
		id, state string
		expiry    int64
	}
	parcels := []parcel{}
	for rows.Next() {
		var p parcel
		if e = rows.Scan(&p.id, &p.state, &p.expiry); e != nil {
			rows.Close()
			return e
		}
		parcels = append(parcels, p)
	}
	e = rows.Err()
	rows.Close()
	if e != nil {
		return e
	}
	for _, p := range parcels {
		if p.state == "uploading" && p.expiry > now {
			continue
		}
		rows, e := a.db.Query("SELECT id FROM files WHERE parcel=?", p.id)
		if e != nil {
			return e
		}
		active := false
		for rows.Next() {
			var id string
			if e = rows.Scan(&id); e != nil {
				rows.Close()
				return e
			}
			if a.activeFiles[id] {
				active = true
			}
		}
		e = rows.Err()
		rows.Close()
		if e != nil {
			return e
		}
		if active {
			continue
		}
		if p.state == "uploading" {
			if _, e = a.db.Exec("UPDATE parcels SET state='expired',version=version+1 WHERE id=?", p.id); e != nil {
				return e
			}
		}
		if e = a.settleUsage(p.id); e != nil {
			return e
		}
		if _, e = a.db.Exec("UPDATE files SET status='deleting' WHERE parcel=?", p.id); e != nil {
			return e
		}
	}
	rows, e = a.db.Query("SELECT f.id,COALESCE(f.object_id,''),f.status,f.expires,f.remaining,p.state FROM files f JOIN parcels p ON p.id=f.parcel WHERE f.status!='deleted'")
	if e != nil {
		return e
	}
	type file struct {
		id, object, status, state string
		expiry                    int64
		remaining                 int
	}
	files := []file{}
	for rows.Next() {
		var f file
		if e = rows.Scan(&f.id, &f.object, &f.status, &f.expiry, &f.remaining, &f.state); e != nil {
			rows.Close()
			return e
		}
		files = append(files, f)
	}
	e = rows.Err()
	rows.Close()
	if e != nil {
		return e
	}
	for _, f := range files {
		if a.activeFiles[f.id] || a.activeObjects[f.object] > 0 {
			continue
		}
		remove := f.status == "deleting" || f.status == "missing" || (f.state == "ready" && (f.remaining == 0 || f.expiry <= now))
		if !remove {
			continue
		}
		if e = a.root.Remove("tmp/" + f.id); e != nil && !errors.Is(e, os.ErrNotExist) {
			return e
		}
		if _, e = a.db.Exec("UPDATE files SET status='deleted',reserved=0,object_id=NULL WHERE id=?", f.id); e != nil {
			return e
		}
	}
	// Objects remain charged until unlink succeeds. Sharing records never unlink each other's payloads.
	rows, e = a.db.Query("SELECT id FROM objects WHERE NOT EXISTS(SELECT 1 FROM files WHERE object_id=objects.id)")
	if e != nil {
		return e
	}
	ids := []string{}
	for rows.Next() {
		var id string
		if e = rows.Scan(&id); e != nil {
			rows.Close()
			return e
		}
		ids = append(ids, id)
	}
	e = rows.Err()
	rows.Close()
	if e != nil {
		return e
	}
	for _, id := range ids {
		if a.activeObjects[id] > 0 {
			continue
		}
		if e = a.root.Remove(objectPath(id)); e != nil && !errors.Is(e, os.ErrNotExist) {
			return e
		}
		if _, e = a.db.Exec("DELETE FROM objects WHERE id=?", id); e != nil {
			return e
		}
	}
	if _, e = a.db.Exec("UPDATE parcels SET state='exhausted',version=version+1 WHERE state='ready' AND NOT EXISTS(SELECT 1 FROM files WHERE parcel=parcels.id AND status='ready' AND remaining>0)"); e != nil {
		return e
	}
	for _, q := range []struct {
		sql  string
		args []any
	}{
		{"DELETE FROM visitors WHERE expires<=?", []any{now}}, {"DELETE FROM grants WHERE expires<=?", []any{now}}, {"DELETE FROM admin_sessions WHERE expires<=?", []any{now}}, {"DELETE FROM usage WHERE day<?", []any{a.now().UTC().AddDate(0, 0, -8).Format("2006-01-02")}}, {"DELETE FROM downloads WHERE created<?", []any{now - 30*86400}}, {"DELETE FROM parcels WHERE state IN('revoked','expired','exhausted') AND created<? AND NOT EXISTS(SELECT 1 FROM files WHERE parcel=parcels.id AND status!='deleted')", []any{now - 30*86400}},
	} {
		if _, e = a.db.Exec(q.sql, q.args...); e != nil {
			return e
		}
	}
	if e = a.trimAudit(); e != nil {
		return e
	}
	entries, e := fs.ReadDir(a.root.FS(), "quarantine")
	if e != nil {
		return e
	}
	for _, d := range entries {
		st, e := d.Info()
		if e != nil {
			return e
		}
		if now-st.ModTime().Unix() > 86400 {
			if e = a.root.Remove("quarantine/" + d.Name()); e != nil {
				return e
			}
		}
	}
	if e = a.scanOrphans(); e != nil {
		return e
	}
	a.extraDisk = 0
	e = fs.WalkDir(a.root.FS(), "quarantine", func(path string, d fs.DirEntry, e error) error {
		if e != nil {
			return e
		}
		st, e := d.Info()
		if e == nil {
			a.extraDisk += allocated(st)
		}
		return e
	})
	if e != nil {
		return e
	}
	_, e = a.db.Exec("PRAGMA wal_checkpoint(PASSIVE)")
	return e
}
func (a *App) InvalidateRestored() error {
	_, e := a.db.Exec("UPDATE parcels SET state='restored',code_hash=NULL,manage_hash=lower(hex(randomblob(32))),version=version+1; DELETE FROM grants; DELETE FROM admin_sessions; DELETE FROM visitors;")
	return e
}
func safeRelative(s string) bool {
	return s != "" && !strings.HasPrefix(s, "/") && !strings.Contains(s, "\\") && fs.ValidPath(s)
}

func (a *App) scanOrphans() error {
	rows, e := a.db.Query("SELECT id FROM objects")
	if e != nil {
		return e
	}
	known := map[string]bool{}
	for rows.Next() {
		var id string
		if e = rows.Scan(&id); e != nil {
			rows.Close()
			return e
		}
		known[id] = true
	}
	e = rows.Err()
	rows.Close()
	if e != nil {
		return e
	}
	return fs.WalkDir(a.root.FS(), "objects", func(path string, d fs.DirEntry, e error) error {
		if e != nil {
			return e
		}
		if d.Type()&os.ModeSymlink != 0 {
			return errors.New("对象目录存在符号链接")
		}
		if d.IsDir() {
			return nil
		}
		if !known[d.Name()] {
			return a.root.Rename(path, "quarantine/"+randomID())
		}
		return nil
	})
}