package core

import (
	"html/template"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/gobuffalo/packr/v2"
	"github.com/gorilla/securecookie"
	"github.com/gorilla/sessions"
	"github.com/op/go-logging"
)

// Engine struct
type Engine struct {
	Localizer
	ORM
	Sentry
	Utils
	ginEngine    *gin.Engine
	httpClient   *http.Client
	Logger       *logging.Logger
	csrf         *CSRF
	Sessions     sessions.Store
	Config       ConfigInterface
	LogFormatter logging.Formatter
	prepared     bool
}

// New Engine instance (must be configured manually, gin can be accessed via engine.Router() directly or engine.ConfigureRouter(...) with callback)
func New() *Engine {
	return &Engine{
		Config:    nil,
		Localizer: Localizer{},
		ORM:       ORM{},
		Sentry:    Sentry{},
		Utils:     Utils{},
		ginEngine: nil,
		Logger:    nil,
		prepared:  false,
	}
}

func (e *Engine) initGin() {
	if !e.Config.IsDebug() {
		gin.SetMode(gin.ReleaseMode)
	}

	r := gin.New()
	r.Use(gin.Recovery())

	if e.Config.IsDebug() {
		r.Use(gin.Logger())
	}

	r.Use(e.LocalizationMiddleware(), e.ErrorMiddleware())
	e.ginEngine = r
}

// Prepare engine for start
func (e *Engine) Prepare() *Engine {
	if e.prepared {
		panic("engine already initialized")
	}
	if e.Config == nil {
		panic("engine.Config must be loaded before initializing")
	}

	if e.DefaultError == "" {
		e.DefaultError = "error"
	}
	if e.LogFormatter == nil {
		e.LogFormatter = DefaultLogFormatter()
	}
	if e.LocaleBundle == nil {
		e.LocaleBundle = DefaultLocalizerBundle()
	}
	if e.LocaleMatcher == nil {
		e.LocaleMatcher = DefaultLocalizerMatcher()
	}

	e.LoadTranslations()
	e.createDB(e.Config.GetDBConfig())
	e.createRavenClient(e.Config.GetSentryDSN())
	e.resetUtils(e.Config.GetAWSConfig(), e.Config.IsDebug(), 0)
	e.Logger = NewLogger(e.Config.GetTransportInfo().GetCode(), e.Config.GetLogLevel(), e.LogFormatter)
	e.Sentry.Localizer = &e.Localizer
	e.Utils.Logger = e.Logger
	e.Sentry.Logger = e.Logger
	e.prepared = true

	return e
}

// TemplateFuncMap combines func map for templates
func (e *Engine) TemplateFuncMap(functions template.FuncMap) template.FuncMap {
	funcMap := e.LocalizationFuncMap()

	for name, fn := range functions {
		funcMap[name] = fn
	}

	funcMap["version"] = func() string {
		return e.Config.GetVersion()
	}

	return funcMap
}

// CreateRenderer with translation function
func (e *Engine) CreateRenderer(callback func(*Renderer), funcs template.FuncMap) Renderer {
	renderer := NewRenderer(e.TemplateFuncMap(funcs))
	callback(&renderer)
	return renderer
}

// CreateRendererFS with translation function and packr box with templates data
func (e *Engine) CreateRendererFS(box *packr.Box, callback func(*Renderer), funcs template.FuncMap) Renderer {
	renderer := NewRenderer(e.TemplateFuncMap(funcs))
	renderer.TemplatesBox = box
	callback(&renderer)
	return renderer
}

// Router will return current gin.Engine or panic if it's not present
func (e *Engine) Router() *gin.Engine {
	if !e.prepared {
		panic("prepare engine first")
	}
	if e.ginEngine == nil {
		e.initGin()
	}

	return e.ginEngine
}

// BuildHTTPClient builds HTTP client with provided configuration
func (e *Engine) BuildHTTPClient(replaceDefault ...bool) *Engine {
	if e.Config.GetHTTPClientConfig() != nil {
		client, err := NewHTTPClientBuilder().
			WithLogger(e.Logger).
			SetLogging(e.Config.IsDebug()).
			FromEngine(e).Build(replaceDefault...)

		if err != nil {
			panic(err)
		} else {
			e.httpClient = client
		}
	}

	return e
}

// SetHTTPClient sets HTTP client to engine
func (e *Engine) SetHTTPClient(client *http.Client) *Engine {
	if client != nil {
		e.httpClient = client
	}

	return e
}

// HTTPClient returns inner http client or default http client
func (e *Engine) HTTPClient() *http.Client {
	if e.httpClient == nil {
		return http.DefaultClient
	}

	return e.httpClient
}

// WithCookieSessions generates new CookieStore with optional key length.
// Default key length is 32 bytes.
func (e *Engine) WithCookieSessions(keyLength ...int) *Engine {
	length := 32

	if len(keyLength) > 0 && keyLength[0] > 0 {
		length = keyLength[0]
	}

	e.Sessions = sessions.NewCookieStore(securecookie.GenerateRandomKey(length))
	return e
}

// WithFilesystemSessions generates new FilesystemStore with optional key length.
// Default key length is 32 bytes.
func (e *Engine) WithFilesystemSessions(path string, keyLength ...int) *Engine {
	length := 32

	if len(keyLength) > 0 && keyLength[0] > 0 {
		length = keyLength[0]
	}

	e.Sessions = sessions.NewFilesystemStore(path, securecookie.GenerateRandomKey(length))
	return e
}

// InitCSRF initializes CSRF middleware. engine.Sessions must be already initialized,
// use engine.WithCookieStore or engine.WithFilesystemStore for that.
// Syntax is similar to core.NewCSRF, but you shouldn't pass sessionName, store and salt.
func (e *Engine) InitCSRF(secret string, abortFunc CSRFAbortFunc, getter CSRFTokenGetter) *Engine {
	if e.Sessions == nil {
		panic("engine.Sessions must be initialized first")
	}

	e.csrf = NewCSRF("", secret, "", e.Sessions, abortFunc, getter)
	return e
}

// VerifyCSRFMiddleware returns CSRF verifier middleware
// Usage:
// 		engine.Router().Use(engine.VerifyCSRFMiddleware(core.DefaultIgnoredMethods))
func (e *Engine) VerifyCSRFMiddleware(ignoredMethods []string) gin.HandlerFunc {
	if e.csrf == nil {
		panic("csrf is not initialized")
	}

	return e.csrf.VerifyCSRFMiddleware(ignoredMethods)
}

// GenerateCSRFMiddleware returns CSRF generator middleware
// Usage:
// 		engine.Router().Use(engine.GenerateCSRFMiddleware())
func (e *Engine) GenerateCSRFMiddleware() gin.HandlerFunc {
	if e.csrf == nil {
		panic("csrf is not initialized")
	}

	return e.csrf.GenerateCSRFMiddleware()
}

// GetCSRFToken returns CSRF token from provided context
func (e *Engine) GetCSRFToken(c *gin.Context) string {
	if e.csrf == nil {
		panic("csrf is not initialized")
	}

	return e.csrf.CSRFFromContext(c)
}

// ConfigureRouter will call provided callback with current gin.Engine, or panic if engine is not present
func (e *Engine) ConfigureRouter(callback func(*gin.Engine)) *Engine {
	callback(e.Router())
	return e
}

// Run gin.Engine loop, or panic if engine is not present
func (e *Engine) Run() error {
	return e.Router().Run(e.Config.GetHTTPConfig().Listen)
}