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"
    graphql "reichard.io/imagini/graph/model"
)

func (api *API) loginHandler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Access-Control-Allow-Origin", "*")
    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, Path: "/", HttpOnly: true}
    refreshCookie := http.Cookie{Name: "RefreshToken", Value: refreshToken, Path: "/", 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)
}

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

    if *requestedDevice.ID == "" {
        err := api.DB.CreateDevice(&requestedDevice)
        createdDevice, err := api.DB.Device(&requestedDevice)
        return createdDevice, err
    }

    foundDevice, err := api.DB.Device(&graphql.Device{
        ID: requestedDevice.ID,
        User: &user,
    })

    return foundDevice, err
}

func deriveDeviceType(r *http.Request) graphql.DeviceType {
    userAgent := strings.ToLower(r.Header.Get("User-Agent"))
    if strings.HasPrefix(userAgent, "ios-imagini"){
        return graphql.DeviceTypeIOs
    } else if strings.HasPrefix(userAgent, "android-imagini"){
        return graphql.DeviceTypeAndroid
    } else if strings.HasPrefix(userAgent, "chrome"){
        return graphql.DeviceTypeChrome
    } else if strings.HasPrefix(userAgent, "firefox"){
        return graphql.DeviceTypeFirefox
    } else if strings.HasPrefix(userAgent, "msie"){
        return graphql.DeviceTypeInternetExplorer
    } else if strings.HasPrefix(userAgent, "edge"){
        return graphql.DeviceTypeEdge
    } else if strings.HasPrefix(userAgent, "safari"){
        return graphql.DeviceTypeSafari
    }
    return graphql.DeviceTypeUnknown
}

func deriveRequestedDevice(r *http.Request) graphql.Device {
    deviceSkeleton := graphql.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 != "deviceid" && key != "devicename" {
            continue
        }

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

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

    return deviceSkeleton
}

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

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

    // Acquire User & Device (Trusted)
    did, ok := refreshToken.Get("did")
    if !ok {
        return nil, err
    }
    uid, ok := refreshToken.Get(jwt.SubjectKey)
    if !ok {
        return nil, err
    }
    deviceUUID, err := uuid.Parse(fmt.Sprintf("%v", did))
    if err != nil {
        return nil, err
    }
    userUUID, err := uuid.Parse(fmt.Sprintf("%v", uid))
    if err != nil {
        return nil, err
    }

    stringUserUUID := userUUID.String()
    stringDeviceUUID := deviceUUID.String()

    // Device & User Skeleton
    user := graphql.User{ID: &stringUserUUID}
    device := graphql.Device{ID: &stringDeviceUUID}

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

    // TODO: Update Refresh Key & Token

    // Convert to jwt.Token
    accessTokenBytes := []byte(accessTokenString)
    accessToken, err := jwt.ParseBytes(accessTokenBytes)

    return accessToken, err
}

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