/* Under Heavy Construction */
package common

import (
	"database/sql"
	"encoding/json"
	"errors"
	"log"
	"sort"
	"strconv"
	"sync"

	qgen "git.tuxpa.in/a/gosora/query_gen"
)

var Groups GroupStore

// ? - We could fallback onto the database when an item can't be found in the cache?
type GroupStore interface {
    LoadGroups() error
    DirtyGet(id int) *Group
    Get(id int) (*Group, error)
    GetCopy(id int) (Group, error)
    Exists(id int) bool
    Create(name, tag string, isAdmin, isMod, isBanned bool) (id int, err error)
    GetAll() ([]*Group, error)
    GetRange(lower, higher int) ([]*Group, error)
    Reload(id int) error // ? - Should we move this to GroupCache? It might require us to do some unnecessary casting though
    Count() int
}

type GroupCache interface {
    CacheSet(g *Group) error
    SetCanSee(gid int, canSee []int) error
    CacheAdd(g *Group) error
    Length() int
}

type MemoryGroupStore struct {
    groups     map[int]*Group // TODO: Use a sync.Map instead of a map?
    groupCount int
    getAll     *sql.Stmt
    get        *sql.Stmt
    count      *sql.Stmt
    userCount  *sql.Stmt

    sync.RWMutex
}

func NewMemoryGroupStore() (*MemoryGroupStore, error) {
    acc := qgen.NewAcc()
    ug := "users_groups"
    return &MemoryGroupStore{
        groups:     make(map[int]*Group),
        groupCount: 0,
        getAll:     acc.Select(ug).Columns("gid,name,permissions,plugin_perms,is_mod,is_admin,is_banned,tag").Prepare(),
        get:        acc.Select(ug).Columns("name,permissions,plugin_perms,is_mod,is_admin,is_banned,tag").Where("gid=?").Prepare(),
        count:      acc.Count(ug).Prepare(),
        userCount:  acc.Count("users").Where("group=?").Prepare(),
    }, acc.FirstError()
}

// TODO: Move this query from the global stmt store into this store
func (s *MemoryGroupStore) LoadGroups() error {
    s.Lock()
    defer s.Unlock()
    s.groups[0] = &Group{ID: 0, Name: "Unknown"}

    rows, err := s.getAll.Query()
    if err != nil {
        return err
    }
    defer rows.Close()

    i := 1
    for ; rows.Next(); i++ {
        g := &Group{ID: 0}
        err := rows.Scan(&g.ID, &g.Name, &g.PermissionsText, &g.PluginPermsText, &g.IsMod, &g.IsAdmin, &g.IsBanned, &g.Tag)
        if err != nil {
            return err
        }

        err = s.initGroup(g)
        if err != nil {
            return err
        }
        s.groups[g.ID] = g
    }
    if err = rows.Err(); err != nil {
        return err
    }
    s.groupCount = i

    DebugLog("Binding the Not Loggedin Group")
    GuestPerms = s.dirtyGetUnsafe(6).Perms // ! Race?
    TopicListThaw.Thaw()
    return nil
}

// TODO: Hit the database when the item isn't in memory
func (s *MemoryGroupStore) dirtyGetUnsafe(id int) *Group {
    group, ok := s.groups[id]
    if !ok {
        return &blankGroup
    }
    return group
}

// TODO: Hit the database when the item isn't in memory
func (s *MemoryGroupStore) DirtyGet(id int) *Group {
    s.RLock()
    group, ok := s.groups[id]
    s.RUnlock()
    if !ok {
        return &blankGroup
    }
    return group
}

// TODO: Hit the database when the item isn't in memory
func (s *MemoryGroupStore) Get(id int) (*Group, error) {
    s.RLock()
    group, ok := s.groups[id]
    s.RUnlock()
    if !ok {
        return nil, ErrNoRows
    }
    return group, nil
}

// TODO: Hit the database when the item isn't in memory
func (s *MemoryGroupStore) GetCopy(id int) (Group, error) {
    s.RLock()
    group, ok := s.groups[id]
    s.RUnlock()
    if !ok {
        return blankGroup, ErrNoRows
    }
    return *group, nil
}

func (s *MemoryGroupStore) Reload(id int) error {
    // TODO: Reload this data too
    g, e := s.Get(id)
    if e != nil {
        LogError(errors.New("can't get cansee data for group #" + strconv.Itoa(id)))
        return nil
    }
    canSee := g.CanSee

    g = &Group{ID: id, CanSee: canSee}
    e = s.get.QueryRow(id).Scan(&g.Name, &g.PermissionsText, &g.PluginPermsText, &g.IsMod, &g.IsAdmin, &g.IsBanned, &g.Tag)
    if e != nil {
        return e
    }
    if e = s.initGroup(g); e != nil {
        LogError(e)
        return nil
    }

    s.CacheSet(g)
    TopicListThaw.Thaw()
    return nil
}

func (s *MemoryGroupStore) initGroup(g *Group) error {
    e := json.Unmarshal(g.PermissionsText, &g.Perms)
    if e != nil {
        log.Printf("g: %+v\n", g)
        log.Print("bad group perms: ", g.PermissionsText)
        return e
    }
    DebugLogf(g.Name+": %+v\n", g.Perms)

    e = json.Unmarshal(g.PluginPermsText, &g.PluginPerms)
    if e != nil {
        log.Printf("g: %+v\n", g)
        log.Print("bad group plugin perms: ", g.PluginPermsText)
        return e
    }
    DebugLogf(g.Name+": %+v\n", g.PluginPerms)

    //group.Perms.ExtData = make(map[string]bool)
    // TODO: Can we optimise the bit where this cascades down to the user now?
    if g.IsAdmin || g.IsMod {
        g.IsBanned = false
    }

    e = s.userCount.QueryRow(g.ID).Scan(&g.UserCount)
    if e != sql.ErrNoRows {
        return e
    }
    return nil
}

func (s *MemoryGroupStore) SetCanSee(gid int, canSee []int) error {
    s.Lock()
    group, ok := s.groups[gid]
    if !ok {
        s.Unlock()
        return nil
    }
    ngroup := &Group{}
    *ngroup = *group
    ngroup.CanSee = canSee
    s.groups[group.ID] = ngroup
    s.Unlock()
    return nil
}

func (s *MemoryGroupStore) CacheSet(g *Group) error {
    s.Lock()
    s.groups[g.ID] = g
    s.Unlock()
    return nil
}

// TODO: Hit the database when the item isn't in memory
func (s *MemoryGroupStore) Exists(id int) bool {
    s.RLock()
    group, ok := s.groups[id]
    s.RUnlock()
    return ok && group.Name != ""
}

// ? Allow two groups with the same name?
// TODO: Refactor this
func (s *MemoryGroupStore) Create(name, tag string, isAdmin, isMod, isBanned bool) (gid int, err error) {
    permstr := "{}"
    tx, err := qgen.Builder.Begin()
    if err != nil {
        return 0, err
    }
    defer tx.Rollback()

    insertTx, err := qgen.Builder.SimpleInsertTx(tx, "users_groups", "name,tag,is_admin,is_mod,is_banned,permissions,plugin_perms", "?,?,?,?,?,?,'{}'")
    if err != nil {
        return 0, err
    }
    res, err := insertTx.Exec(name, tag, isAdmin, isMod, isBanned, permstr)
    if err != nil {
        return 0, err
    }
    gid64, err := res.LastInsertId()
    if err != nil {
        return 0, err
    }
    gid = int(gid64)

    perms := BlankPerms
    blankIntList := []int{}
    pluginPerms := make(map[string]bool)
    pluginPermsBytes := []byte("{}")
    GetHookTable().Vhook("create_group_preappend", &pluginPerms, &pluginPermsBytes)

    // Generate the forum permissions based on the presets...
    forums, err := Forums.GetAll()
    if err != nil {
        return 0, err
    }

    presetSet := make(map[int]string)
    permSet := make(map[int]*ForumPerms)
    for _, f := range forums {
        var thePreset string
        switch {
        case isAdmin:
            thePreset = "admins"
        case isMod:
            thePreset = "staff"
        case isBanned:
            thePreset = "banned"
        default:
            thePreset = "members"
        }

        permmap := PresetToPermmap(f.Preset)
        permItem := permmap[thePreset]
        permItem.Overrides = true

        permSet[f.ID] = permItem
        presetSet[f.ID] = f.Preset
    }

    err = ReplaceForumPermsForGroupTx(tx, gid, presetSet, permSet)
    if err != nil {
        return 0, err
    }
    err = tx.Commit()
    if err != nil {
        return 0, err
    }

    // TODO: Can we optimise the bit where this cascades down to the user now?
    if isAdmin || isMod {
        isBanned = false
    }

    s.CacheAdd(&Group{gid, name, isMod, isAdmin, isBanned, tag, perms, []byte(permstr), pluginPerms, pluginPermsBytes, blankIntList, 0})

    TopicListThaw.Thaw()
    return gid, FPStore.ReloadAll()
    //return gid, TopicList.RebuildPermTree()
}

func (s *MemoryGroupStore) CacheAdd(g *Group) error {
    s.Lock()
    s.groups[g.ID] = g
    s.groupCount++
    s.Unlock()
    return nil
}

func (s *MemoryGroupStore) GetAll() (results []*Group, err error) {
    var i int
    s.RLock()
    results = make([]*Group, len(s.groups))
    for _, group := range s.groups {
        results[i] = group
        i++
    }
    s.RUnlock()
    sort.Sort(SortGroup(results))
    return results, nil
}

func (s *MemoryGroupStore) GetAllMap() (map[int]*Group, error) {
    s.RLock()
    defer s.RUnlock()
    return s.groups, nil
}

// ? - Set the lower and higher numbers to 0 to remove the bounds
// TODO: Might be a little slow right now, maybe we can cache the groups in a slice or break the map up into chunks
func (s *MemoryGroupStore) GetRange(lower, higher int) (groups []*Group, err error) {
    if lower == 0 && higher == 0 {
        return s.GetAll()
    }

    // TODO: Simplify these four conditionals into two
    if lower == 0 {
        if higher < 0 {
            return nil, errors.New("higher may not be lower than 0")
        }
    } else if higher == 0 {
        if lower < 0 {
            return nil, errors.New("lower may not be lower than 0")
        }
    }

    s.RLock()
    for gid, group := range s.groups {
        if gid >= lower && (gid <= higher || higher == 0) {
            groups = append(groups, group)
        }
    }
    s.RUnlock()
    sort.Sort(SortGroup(groups))

    return groups, nil
}

func (s *MemoryGroupStore) Length() int {
    s.RLock()
    defer s.RUnlock()
    return s.groupCount
}

func (s *MemoryGroupStore) Count() (count int) {
    err := s.count.QueryRow().Scan(&count)
    if err != nil {
        LogError(err)
    }
    return count
}