package api

import (
    "fmt"
    "time"
    "strings"
    "net/http"
    "encoding/json"
    "github.com/google/uuid"
    log "github.com/sirupsen/logrus"
    "github.com/lestrrat-go/jwx/jwt"

    "reichard.io/imagini/internal/models"
)

func (api *API) loginHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodPost {
        errorJSON(w, "Method is not supported.", http.StatusMethodNotAllowed)
        return
    }

    // Decode into Struct
    var creds models.APICredentials
    err := json.NewDecoder(r.Body).Decode(&creds)
    if err != nil {
        errorJSON(w, "Invalid parameters.", http.StatusBadRequest)
        return
    }

    // Validate
    if creds.User == "" || creds.Password == "" {
        errorJSON(w, "Invalid parameters.", http.StatusBadRequest)
        return
    }

    // Do login
    resp, user := api.Auth.AuthenticateUser(creds)
    if !resp {
        errorJSON(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }

    // Upsert device
    device, err := api.upsertRequestedDevice(user, r)
    if err != nil {
        log.Error("[api] loginHandler - Failed to upsert device: ", err)
        errorJSON(w, "DB error. Unable to proceed.", http.StatusUnauthorized)
        return
    }

    // Create Tokens
    accessToken, err := api.Auth.CreateJWTAccessToken(user, device)
    refreshToken, err := api.Auth.CreateJWTRefreshToken(user, device)

    // Set appropriate cookies
    accessCookie := http.Cookie{Name: "AccessToken", Value: accessToken, HttpOnly: true}
    refreshCookie := http.Cookie{Name: "RefreshToken", Value: refreshToken, HttpOnly: true}
    http.SetCookie(w, &accessCookie)
    http.SetCookie(w, &refreshCookie)

    // Response success
    successJSON(w, "Login success.", http.StatusOK)
}

func (api *API) logoutHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodPost {
        http.Error(w, "Method is not supported.", http.StatusMethodNotAllowed)
        return
    }

    // TODO: Reset Refresh Key

    // Clear Cookies
    http.SetCookie(w, &http.Cookie{Name: "AccessToken", Expires: time.Unix(0, 0)})
    http.SetCookie(w, &http.Cookie{Name: "RefreshToken", Expires: time.Unix(0, 0)})

    successJSON(w, "Logout success.", http.StatusOK)
}

func (api *API) refreshLoginHandler(w http.ResponseWriter, r *http.Request) {
    refreshCookie, err := r.Cookie("RefreshToken")
    if err != nil {
        log.Warn("[middleware] Cookie not found")
        w.WriteHeader(http.StatusUnauthorized)
        return
    }

    // Validate Refresh Token
    refreshToken, ok := api.Auth.ValidateJWTRefreshToken(refreshCookie.Value)
    if !ok {
        http.SetCookie(w, &http.Cookie{Name: "AccessToken", Expires: time.Unix(0, 0)})
        http.SetCookie(w, &http.Cookie{Name: "RefreshToken", Expires: time.Unix(0, 0)})
        errorJSON(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }

    // Acquire User & Device (Trusted)
    did, ok := refreshToken.Get("did")
    if !ok {
        errorJSON(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }
    uid, ok := refreshToken.Get(jwt.SubjectKey)
    if !ok {
        errorJSON(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }
    deviceID, err := uuid.Parse(fmt.Sprintf("%v", did))
    if err != nil {
        errorJSON(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }
    userID, err := uuid.Parse(fmt.Sprintf("%v", uid))
    if err != nil {
        errorJSON(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }

    // Device Skeleton
    user := models.User{Base: models.Base{UUID: userID}}
    device := models.Device{Base: models.Base{UUID: deviceID}}

    // Update token
    accessToken, err := api.Auth.CreateJWTAccessToken(user, device)
    accessCookie := http.Cookie{Name: "AccessToken", Value: accessToken}
    http.SetCookie(w, &accessCookie)

    // Response success
    successJSON(w, "Refresh success.", http.StatusOK)
}

/**
 * This will find or create the requested device based on ID and User.
 **/
func (api *API) upsertRequestedDevice(user models.User, r *http.Request) (models.Device, error) {
    requestedDevice := deriveRequestedDevice(r)
    requestedDevice.Type = deriveDeviceType(r)
    requestedDevice.User = user

    if requestedDevice.UUID == uuid.Nil {
        createdDevice, err := api.DB.CreateDevice(requestedDevice)
        return createdDevice, err
    }

    foundDevice, err := api.DB.Device(models.Device{
        Base: models.Base{ UUID: requestedDevice.UUID },
        User: user,
    })

    return foundDevice, err
}

func deriveDeviceType(r *http.Request) string {
    userAgent := strings.ToLower(r.Header.Get("User-Agent"))
    if strings.HasPrefix(userAgent, "ios-imagini"){
        return "iOS"
    } else if strings.HasPrefix(userAgent, "android-imagini"){
        return "Android"
    } else if strings.HasPrefix(userAgent, "chrome"){
        return "Chrome"
    } else if strings.HasPrefix(userAgent, "firefox"){
        return "Firefox"
    } else if strings.HasPrefix(userAgent, "msie"){
        return "Internet Explorer"
    } else if strings.HasPrefix(userAgent, "edge"){
        return "Edge"
    } else if strings.HasPrefix(userAgent, "safari"){
        return "Safari"
    }
    return "Unknown"
}

func deriveRequestedDevice(r *http.Request) models.Device {
    deviceSkeleton := models.Device{}
    authHeader := r.Header.Get("X-Imagini-Authorization")
    splitAuthInfo := strings.Split(authHeader, ",")

    // For each Key - Value pair
    for i := range splitAuthInfo {

        // Split Key - Value
        item := strings.TrimSpace(splitAuthInfo[i])
        splitItem := strings.SplitN(item, "=", 2)
        if len(splitItem) != 2 {
            continue
        }

        // Derive Key
        key := strings.ToLower(strings.TrimSpace(splitItem[0]))
        if key != "deviceuuid" && key != "devicename" {
            continue
        }

        // Derive Value
        val := trimQuotes(strings.ToLower(strings.TrimSpace(splitItem[1])))
        if key == "deviceuuid" {
            parsedDeviceUUID, err := uuid.Parse(val)
            if err != nil {
                log.Warn("[auth] deriveRequestedDevice - Unable to parse requested DeviceUUID: ", val)
                continue
            }
            deviceSkeleton.Base = models.Base{UUID: parsedDeviceUUID}
        } else if key == "devicename" {
            deviceSkeleton.Name = val
        }
    }

    // If name not set, set to type
    if deviceSkeleton.Name == "" {
        deviceSkeleton.Name = deviceSkeleton.Type
    }

    return deviceSkeleton
}

func trimQuotes(s string) string {
    if len(s) >= 2 {
        if s[0] == '"' && s[len(s)-1] == '"' {
            return s[1 : len(s)-1]
        }
    }
    return s
}