package common

import (
	"crypto/subtle"
	"html"
	"io"
	"net"
	"net/http"
	"os"
	"regexp"
	"strconv"
	"strings"
	"time"

	"git.tuxpa.in/a/gosora/common/phrases"
	"git.tuxpa.in/a/gosora/uutils"
)

// nolint
var PreRoute func(http.ResponseWriter, *http.Request) (User, bool) = preRoute

// TODO: Come up with a better middleware solution
// nolint We need these types so people can tell what they are without scrolling to the bottom of the file
var PanelUserCheck func(http.ResponseWriter, *http.Request, *User) (*Header, PanelStats, RouteError) = panelUserCheck
var SimplePanelUserCheck func(http.ResponseWriter, *http.Request, *User) (*HeaderLite, RouteError) = simplePanelUserCheck
var SimpleForumUserCheck func(w http.ResponseWriter, r *http.Request, u *User, fid int) (headerLite *HeaderLite, err RouteError) = simpleForumUserCheck
var ForumUserCheck func(h *Header, w http.ResponseWriter, r *http.Request, u *User, fid int) (err RouteError) = forumUserCheck
var SimpleUserCheck func(w http.ResponseWriter, r *http.Request, u *User) (headerLite *HeaderLite, err RouteError) = simpleUserCheck
var UserCheck func(w http.ResponseWriter, r *http.Request, u *User) (h *Header, err RouteError) = userCheck
var UserCheckNano func(w http.ResponseWriter, r *http.Request, u *User, nano int64) (h *Header, err RouteError) = userCheck2

func simpleForumUserCheck(w http.ResponseWriter, r *http.Request, u *User, fid int) (h *HeaderLite, rerr RouteError) {
    h, rerr = SimpleUserCheck(w, r, u)
    if rerr != nil {
        return h, rerr
    }
    if !Forums.Exists(fid) {
        return nil, PreError("The target forum doesn't exist.", w, r)
    }

    // Is there a better way of doing the skip AND the success flag on this hook like multiple returns?
    /*skip, rerr := h.Hooks.VhookSkippable("simple_forum_check_pre_perms", w, r, u, &fid, h)
    if skip || rerr != nil {
        return h, rerr
    }*/
    skip, rerr := H_simple_forum_check_pre_perms_hook(h.Hooks, w, r, u, &fid, h)
    if skip || rerr != nil {
        return h, rerr
    }

    fp, err := FPStore.Get(fid, u.Group)
    if err == ErrNoRows {
        fp = BlankForumPerms()
    } else if err != nil {
        return h, InternalError(err, w, r)
    }
    cascadeForumPerms(fp, u)
    return h, nil
}

func forumUserCheck(h *Header, w http.ResponseWriter, r *http.Request, u *User, fid int) (rerr RouteError) {
    if !Forums.Exists(fid) {
        return NotFound(w, r, h)
    }

    /*skip, rerr := h.Hooks.VhookSkippable("forum_check_pre_perms", w, r, u, &fid, h)
    if skip || rerr != nil {
        return rerr
    }*/
    /*skip, rerr := VhookSkippableTest(h.Hooks, "forum_check_pre_perms", w, r, u, &fid, h)
    if skip || rerr != nil {
        return rerr
    }*/
    skip, rerr := H_forum_check_pre_perms_hook(h.Hooks, w, r, u, &fid, h)
    if skip || rerr != nil {
        return rerr
    }

    fp, err := FPStore.Get(fid, u.Group)
    if err == ErrNoRows {
        fp = BlankForumPerms()
    } else if err != nil {
        return InternalError(err, w, r)
    }
    cascadeForumPerms(fp, u)
    h.CurrentUser = u // TODO: Use a pointer instead for CurrentUser, so we don't have to do this
    return rerr
}

// TODO: Put this on the user instance? Do we really want forum specific logic in there? Maybe, a method which spits a new pointer with the same contents as user?
func cascadeForumPerms(fp *ForumPerms, u *User) {
    if fp.Overrides && !u.IsSuperAdmin {
        u.Perms.ViewTopic = fp.ViewTopic
        u.Perms.LikeItem = fp.LikeItem
        u.Perms.CreateTopic = fp.CreateTopic
        u.Perms.EditTopic = fp.EditTopic
        u.Perms.DeleteTopic = fp.DeleteTopic
        u.Perms.CreateReply = fp.CreateReply
        u.Perms.EditReply = fp.EditReply
        u.Perms.DeleteReply = fp.DeleteReply
        u.Perms.PinTopic = fp.PinTopic
        u.Perms.CloseTopic = fp.CloseTopic
        u.Perms.MoveTopic = fp.MoveTopic

        if len(fp.ExtData) != 0 {
            for name, perm := range fp.ExtData {
                u.PluginPerms[name] = perm
            }
        }
    }
}

// Even if they have the right permissions, the control panel is only open to supermods+. There are many areas without subpermissions which assume that the current user is a supermod+ and admins are extremely unlikely to give these permissions to someone who isn't at-least a supermod to begin with
// TODO: Do a panel specific theme?
func panelUserCheck(w http.ResponseWriter, r *http.Request, u *User) (h *Header, stats PanelStats, rerr RouteError) {
    theme := GetThemeByReq(r)
    h = &Header{
        Site:     Site,
        Settings: SettingBox.Load().(SettingMap),
        //Themes:      Themes,
        ThemesSlice: ThemesSlice,
        Theme:       theme,
        CurrentUser: u,
        Hooks:       GetHookTable(),
        Zone:        "panel",
        Writer:      w,
        IsoCode:     phrases.GetLangPack().IsoCode,
        //StartedAt:   time.Now(),
        StartedAt: uutils.Nanotime(),
    }
    // TODO: We should probably initialise header.ExtData
    // ? - Should we only show this in debug mode? It might be useful for detecting issues in production, if we show it there as-well
    //if user.IsAdmin {
    //h.StartedAt = time.Now()
    //}

    h.AddSheet(theme.Name + "/main.css")
    h.AddSheet(theme.Name + "/panel.css")
    if len(theme.Resources) > 0 {
        rlist := theme.Resources
        for _, res := range rlist {
            if res.LocID == LocGlobal || res.LocID == LocPanel {
                if res.Type == ResTypeSheet {
                    h.AddSheet(res.Name)
                } else if res.Type == ResTypeScript {
                    if res.Async {
                        h.AddScriptAsync(res.Name)
                    } else {
                        h.AddScript(res.Name)
                    }
                }
            }
        }
    }

    //h := w.Header()
    //h.Set("Content-Security-Policy", "default-src 'self'")

    // TODO: GDPR. Add a global control panel notice warning the admins of staff members who don't have 2FA enabled
    stats.Users = Users.Count()
    stats.Groups = Groups.Count()
    stats.Forums = Forums.Count()
    stats.Pages = Pages.Count()
    stats.Settings = len(h.Settings)
    stats.WordFilters = WordFilters.EstCount()
    stats.Themes = len(Themes)
    stats.Reports = 0 // TODO: Do the report count. Only show open threads?

    addPreScript := func(name string, i int) {
        // TODO: Optimise this by removing a superfluous string alloc
        if theme.OverridenMap != nil {
            //fmt.Printf("name %+v\n", name)
            //fmt.Printf("theme.OverridenMap %+v\n", theme.OverridenMap)
            if _, ok := theme.OverridenMap[name]; ok {
                tname := "_" + theme.Name
                //fmt.Printf("tname %+v\n", tname)
                h.AddPreScriptAsync("tmpl_" + name + tname + ".js")
                return
            }
        }
        //fmt.Printf("tname %+v\n", tname)
        h.AddPreScriptAsync(ucstrs[i])
    }
    addPreScript("alert", 3)
    addPreScript("notice", 4)

    return h, stats, nil
}

func simplePanelUserCheck(w http.ResponseWriter, r *http.Request, u *User) (lite *HeaderLite, rerr RouteError) {
    return SimpleUserCheck(w, r, u)
}

// SimpleUserCheck is back from the grave, yay :D
func simpleUserCheck(w http.ResponseWriter, r *http.Request, u *User) (lite *HeaderLite, rerr RouteError) {
    return &HeaderLite{
        Site:     Site,
        Settings: SettingBox.Load().(SettingMap),
        Hooks:    GetHookTable(),
    }, nil
}

func GetThemeByReq(r *http.Request) *Theme {
    theme := &Theme{Name: ""}
    cookie, e := r.Cookie("current_theme")
    if e == nil {
        inTheme, ok := Themes[html.EscapeString(cookie.Value)]
        if ok && !theme.HideFromThemes {
            theme = inTheme
        }
    }
    if theme.Name == "" {
        theme = Themes[DefaultThemeBox.Load().(string)]
    }
    return theme
}

func userCheck(w http.ResponseWriter, r *http.Request, u *User) (h *Header, rerr RouteError) {
    return userCheck2(w, r, u, uutils.Nanotime())
}

// TODO: Add the ability for admins to restrict certain themes to certain groups?
// ! Be careful about firing errors off here as CustomError uses this
func userCheck2(w http.ResponseWriter, r *http.Request, u *User, nano int64) (h *Header, rerr RouteError) {
    theme := GetThemeByReq(r)
    h = &Header{
        Site:     Site,
        Settings: SettingBox.Load().(SettingMap),
        //Themes:      Themes,
        ThemesSlice: ThemesSlice,
        Theme:       theme,
        CurrentUser: u, // ! Some things rely on this being a pointer downstream from this function
        Hooks:       GetHookTable(),
        Zone:        ucstrs[0],
        Writer:      w,
        IsoCode:     phrases.GetLangPack().IsoCode,
        StartedAt:   nano,
    }
    // TODO: Optimise this by avoiding accessing a map string index
    if !u.Loggedin {
        h.GoogSiteVerify = h.Settings["google_site_verify"].(string)
    }

    if u.IsBanned {
        h.AddNotice("account_banned")
    }
    if u.Loggedin && !u.Active {
        h.AddNotice("account_inactive")
    }
    /*h.Scripts, _ = StrSlicePool.Get().([]string)
    if h.Scripts != nil {
        h.Scripts = h.Scripts[:0]
    }
    h.PreScriptsAsync, _ = StrSlicePool.Get().([]string)
    if h.PreScriptsAsync != nil {
        h.PreScriptsAsync = h.PreScriptsAsync[:0]
    }*/

    // An optimisation so we don't populate StartedAt for users who shouldn't see the stat anyway
    // ? - Should we only show this in debug mode? It might be useful for detecting issues in production, if we show it there as-well
    //if u.IsAdmin {
    //h.StartedAt = time.Now()
    //}

    //PrepResources(u,h,theme)
    return h, nil
}

func PrepResources(u *User, h *Header, theme *Theme) {
    h.AddSheet(theme.Name + "/main.css")

    if len(theme.Resources) > 0 {
        rlist := theme.Resources
        for _, res := range rlist {
            if res.Loggedin && !u.Loggedin {
                continue
            }
            if res.LocID == LocGlobal || res.LocID == LocFront {
                if res.Type == ResTypeSheet {
                    h.AddSheet(res.Name)
                } else if res.Type == ResTypeScript {
                    if res.Async {
                        h.AddScriptAsync(res.Name)
                    } else {
                        h.AddScript(res.Name)
                    }
                }
            }
        }
    }

    addPreScript := func(name string, i int) {
        // TODO: Optimise this by removing a superfluous string alloc
        if theme.OverridenMap != nil {
            //fmt.Printf("name %+v\n", name)
            //fmt.Printf("theme.OverridenMap %+v\n", theme.OverridenMap)
            if _, ok := theme.OverridenMap[name]; ok {
                tname := "_" + theme.Name
                //fmt.Printf("tname %+v\n", tname)
                h.AddPreScriptAsync("tmpl_" + name + tname + ".js")
                return
            }
        }
        //fmt.Printf("tname %+v\n", tname)
        h.AddPreScriptAsync(ucstrs[i])
    }
    addPreScript("topics_topic", 1)
    addPreScript("paginator", 2)
    addPreScript("alert", 3)
    addPreScript("notice", 4)
    if u.Loggedin {
        addPreScript("topic_c_edit_post", 5)
        addPreScript("topic_c_attach_item", 6)
        addPreScript("topic_c_poll_input", 7)
    }
}

func pstr(name string) string {
    return "tmpl_" + name + ".js"
}

var ucstrs = [...]string{
    "frontend",

    pstr("topics_topic"),
    pstr("paginator"),
    pstr("alert"),
    pstr("notice"),

    pstr("topic_c_edit_post"),
    pstr("topic_c_attach_item"),
    pstr("topic_c_poll_input"),
}

func preRoute(w http.ResponseWriter, r *http.Request) (User, bool) {
    userptr, halt := Auth.SessionCheck(w, r)
    if halt {
        return *userptr, false
    }
    var usercpy *User = BlankUser()
    *usercpy = *userptr
    usercpy.Init() // TODO: Can we reduce the amount of work we do here?

    // TODO: Add a config setting to disable this header
    // TODO: Have this header cover more things
    if Config.SslSchema {
        w.Header().Set("Content-Security-Policy", "upgrade-insecure-requests")
    }

    // TODO: WIP. Refactor this to eliminate the unnecessary query
    // TODO: Better take proxies into consideration
    if !Config.DisableIP {
        var host string
        // TODO: Prefer Cf-Connecting-Ip header, fewer shenanigans
        if Site.HasProxy {
            // TODO: Check the right-most IP, might get tricky with multiple proxies, maybe have a setting for the number of hops we jump through
            xForwardedFor := r.Header.Get("X-Forwarded-For")
            if xForwardedFor != "" {
                forwardedFor := strings.Split(xForwardedFor, ",")
                // TODO: Check if this is a valid IP Address, reject if not
                host = forwardedFor[len(forwardedFor)-1]
            }
        }

        if host == "" {
            var e error
            host, _, e = net.SplitHostPort(r.RemoteAddr)
            if e != nil {
                _ = PreError("Bad IP", w, r)
                return *usercpy, false
            }
        }

        if !Config.DisableLastIP && usercpy.Loggedin && host != usercpy.GetIP() {
            mon := time.Now().Month()
            e := usercpy.UpdateIP(strconv.Itoa(int(mon)) + "-" + host)
            if e != nil {
                _ = InternalError(e, w, r)
                return *usercpy, false
            }
        }
        usercpy.LastIP = host
    }

    return *usercpy, true
}

func UploadAvatar(w http.ResponseWriter, r *http.Request, u *User, tuid int) (ext string, ferr RouteError) {
    // We don't want multiple files
    // TODO: Are we doing this correctly?
    filenameMap := make(map[string]bool)
    for _, fheaders := range r.MultipartForm.File {
        for _, hdr := range fheaders {
            if hdr.Filename == "" {
                continue
            }
            filenameMap[hdr.Filename] = true
        }
    }
    if len(filenameMap) > 1 {
        return "", LocalError("You may only upload one avatar", w, r, u)
    }

    for _, fheaders := range r.MultipartForm.File {
        for _, hdr := range fheaders {
            if hdr.Filename == "" {
                continue
            }
            inFile, err := hdr.Open()
            if err != nil {
                return "", LocalError("Upload failed", w, r, u)
            }
            defer inFile.Close()

            if ext == "" {
                extarr := strings.Split(hdr.Filename, ".")
                if len(extarr) < 2 {
                    return "", LocalError("Bad file", w, r, u)
                }
                ext = extarr[len(extarr)-1]

                // TODO: Can we do this without a regex?
                reg, err := regexp.Compile("[^A-Za-z0-9]+")
                if err != nil {
                    return "", LocalError("Bad file extension", w, r, u)
                }
                ext = reg.ReplaceAllString(ext, "")
                ext = strings.ToLower(ext)

                if !ImageFileExts.Contains(ext) {
                    return "", LocalError("You can only use an image for your avatar", w, r, u)
                }
            }

            // TODO: Centralise this string, so we don't have to change it in two different places when it changes
            outFile, err := os.Create("./uploads/avatar_" + strconv.Itoa(tuid) + "." + ext)
            if err != nil {
                return "", LocalError("Upload failed [File Creation Failed]", w, r, u)
            }
            defer outFile.Close()

            _, err = io.Copy(outFile, inFile)
            if err != nil {
                return "", LocalError("Upload failed [Copy Failed]", w, r, u)
            }
        }
    }
    if ext == "" {
        return "", LocalError("No file", w, r, u)
    }
    return ext, nil
}

func ChangeAvatar(path string, w http.ResponseWriter, r *http.Request, u *User) RouteError {
    e := u.ChangeAvatar(path)
    if e != nil {
        return InternalError(e, w, r)
    }

    // Clean up the old avatar data, so we don't end up with too many dead files in /uploads/
    if len(u.RawAvatar) > 2 {
        if u.RawAvatar[0] == '.' && u.RawAvatar[1] == '.' {
            e := os.Remove("./uploads/avatar_" + strconv.Itoa(u.ID) + "_tmp" + u.RawAvatar[1:])
            if e != nil && !os.IsNotExist(e) {
                LogWarning(e)
                return LocalError("Something went wrong", w, r, u)
            }
            e = os.Remove("./uploads/avatar_" + strconv.Itoa(u.ID) + "_w48" + u.RawAvatar[1:])
            if e != nil && !os.IsNotExist(e) {
                LogWarning(e)
                return LocalError("Something went wrong", w, r, u)
            }
        }
    }

    return nil
}

// SuperAdminOnly makes sure that only super admin can access certain critical panel routes
func SuperAdminOnly(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if !u.IsSuperAdmin {
        return NoPermissions(w, r, u)
    }
    return nil
}

// AdminOnly makes sure that only admins can access certain panel routes
func AdminOnly(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if !u.IsAdmin {
        return NoPermissions(w, r, u)
    }
    return nil
}

// SuperModeOnly makes sure that only super mods or higher can access the panel routes
func SuperModOnly(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if !u.IsSuperMod {
        return NoPermissions(w, r, u)
    }
    return nil
}

// MemberOnly makes sure that only logged in users can access this route
func MemberOnly(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if !u.Loggedin {
        return LoginRequired(w, r, u)
    }
    return nil
}

// NoBanned stops any banned users from accessing this route
func NoBanned(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if u.IsBanned {
        return Banned(w, r, u)
    }
    return nil
}

func ParseForm(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if e := r.ParseForm(); e != nil {
        return LocalError("Bad Form", w, r, u)
    }
    return nil
}

func NoSessionMismatch(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if e := r.ParseForm(); e != nil {
        return LocalError("Bad Form", w, r, u)
    }
    if len(u.Session) == 0 {
        return SecurityError(w, r, u)
    }
    // TODO: Try to eliminate some of these allocations
    sess := []byte(u.Session)
    if subtle.ConstantTimeCompare([]byte(r.FormValue("session")), sess) != 1 && subtle.ConstantTimeCompare([]byte(r.FormValue("s")), sess) != 1 {
        return SecurityError(w, r, u)
    }
    return nil
}

func ReqIsJson(r *http.Request) bool {
    return r.Header.Get("Content-type") == "application/json"
}

func HandleUploadRoute(w http.ResponseWriter, r *http.Request, u *User, maxFileSize int) RouteError {
    // TODO: Reuse this code more
    if r.ContentLength > int64(maxFileSize) {
        size, unit := ConvertByteUnit(float64(maxFileSize))
        return CustomError("Your upload is too big. Your files need to be smaller than "+strconv.Itoa(int(size))+unit+".", http.StatusExpectationFailed, "Error", w, r, nil, u)
    }
    r.Body = http.MaxBytesReader(w, r.Body, r.ContentLength)

    e := r.ParseMultipartForm(int64(Megabyte))
    if e != nil {
        return LocalError("Bad Form", w, r, u)
    }
    return nil
}

func NoUploadSessionMismatch(w http.ResponseWriter, r *http.Request, u *User) RouteError {
    if len(u.Session) == 0 {
        return SecurityError(w, r, u)
    }
    // TODO: Try to eliminate some of these allocations
    sess := []byte(u.Session)
    if subtle.ConstantTimeCompare([]byte(r.FormValue("session")), sess) != 1 && subtle.ConstantTimeCompare([]byte(r.FormValue("s")), sess) != 1 {
        return SecurityError(w, r, u)
    }
    return nil
}