// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

package api4

import (
	"net/http"
	"reflect"

	"github.com/mattermost/mattermost-server/v5/audit"
	"github.com/mattermost/mattermost-server/v5/config"
	"github.com/mattermost/mattermost-server/v5/model"
	"github.com/mattermost/mattermost-server/v5/utils"
)

func (api *API) InitConfig() {
	api.BaseRoutes.ApiRoot.Handle("/config", api.ApiSessionRequired(getConfig)).Methods("GET")
	api.BaseRoutes.ApiRoot.Handle("/config", api.ApiSessionRequired(updateConfig)).Methods("PUT")
	api.BaseRoutes.ApiRoot.Handle("/config/patch", api.ApiSessionRequired(patchConfig)).Methods("PUT")
	api.BaseRoutes.ApiRoot.Handle("/config/reload", api.ApiSessionRequired(configReload)).Methods("POST")
	api.BaseRoutes.ApiRoot.Handle("/config/client", api.ApiHandler(getClientConfig)).Methods("GET")
	api.BaseRoutes.ApiRoot.Handle("/config/environment", api.ApiSessionRequired(getEnvironmentConfig)).Methods("GET")
}

func getConfig(c *Context, w http.ResponseWriter, r *http.Request) {
	if !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
		return
	}

	auditRec := c.MakeAuditRecord("getConfig", audit.Fail)
	defer c.LogAuditRec(auditRec)

	cfg := c.App.GetSanitizedConfig()

	auditRec.Success()

	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
	w.Write([]byte(cfg.ToJson()))
}

func configReload(c *Context, w http.ResponseWriter, r *http.Request) {
	auditRec := c.MakeAuditRecord("configReload", audit.Fail)
	defer c.LogAuditRec(auditRec)

	if !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
		return
	}

	if *c.App.Config().ExperimentalSettings.RestrictSystemAdmin {
		c.Err = model.NewAppError("configReload", "api.restricted_system_admin", nil, "", http.StatusBadRequest)
		return
	}

	c.App.ReloadConfig()

	auditRec.Success()

	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
	ReturnStatusOK(w)
}

func updateConfig(c *Context, w http.ResponseWriter, r *http.Request) {
	cfg := model.ConfigFromJson(r.Body)
	if cfg == nil {
		c.SetInvalidParam("config")
		return
	}

	auditRec := c.MakeAuditRecord("updateConfig", audit.Fail)
	defer c.LogAuditRec(auditRec)

	cfg.SetDefaults()

	if !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
		return
	}

	appCfg := c.App.Config()
	if *c.App.Config().ExperimentalSettings.RestrictSystemAdmin {
		// Start with the current configuration, and only merge values not marked as being
		// restricted.
		var err error
		cfg, err = config.Merge(appCfg, cfg, &utils.MergeConfig{
			StructFieldFilter: func(structField reflect.StructField, base, patch reflect.Value) bool {
				restricted := structField.Tag.Get("restricted") == "true"

				return !restricted
			},
		})
		if err != nil {
			c.Err = model.NewAppError("updateConfig", "api.config.update_config.restricted_merge.app_error", nil, err.Error(), http.StatusInternalServerError)
		}
	}

	// Do not allow plugin uploads to be toggled through the API
	cfg.PluginSettings.EnableUploads = appCfg.PluginSettings.EnableUploads

	// Do not allow certificates to be changed through the API
	cfg.PluginSettings.SignaturePublicKeyFiles = appCfg.PluginSettings.SignaturePublicKeyFiles

	c.App.HandleMessageExportConfig(cfg, appCfg)

	err := cfg.IsValid()
	if err != nil {
		c.Err = err
		return
	}

	err = c.App.SaveConfig(cfg, true)
	if err != nil {
		c.Err = err
		return
	}

	cfg = c.App.GetSanitizedConfig()

	auditRec.Success()
	c.LogAudit("updateConfig")

	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
	w.Write([]byte(cfg.ToJson()))
}

func getClientConfig(c *Context, w http.ResponseWriter, r *http.Request) {
	format := r.URL.Query().Get("format")

	if format == "" {
		c.Err = model.NewAppError("getClientConfig", "api.config.client.old_format.app_error", nil, "", http.StatusNotImplemented)
		return
	}

	if format != "old" {
		c.SetInvalidParam("format")
		return
	}

	var config map[string]string
	if len(c.App.Session().UserId) == 0 {
		config = c.App.LimitedClientConfigWithComputed()
	} else {
		config = c.App.ClientConfigWithComputed()
	}

	w.Write([]byte(model.MapToJson(config)))
}

func getEnvironmentConfig(c *Context, w http.ResponseWriter, r *http.Request) {
	if !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
		return
	}

	envConfig := c.App.GetEnvironmentConfig()

	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
	w.Write([]byte(model.StringInterfaceToJson(envConfig)))
}

func patchConfig(c *Context, w http.ResponseWriter, r *http.Request) {
	cfg := model.ConfigFromJson(r.Body)
	if cfg == nil {
		c.SetInvalidParam("config")
		return
	}

	auditRec := c.MakeAuditRecord("patchConfig", audit.Fail)
	defer c.LogAuditRec(auditRec)

	if !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
		return
	}

	appCfg := c.App.Config()
	var filterFn utils.StructFieldFilter
	if *appCfg.ExperimentalSettings.RestrictSystemAdmin {
		filterFn = func(structField reflect.StructField, base, patch reflect.Value) bool {
			return !(structField.Tag.Get("restricted") == "true")
		}
	} else {
		filterFn = func(structField reflect.StructField, base, patch reflect.Value) bool {
			return true
		}
	}

	// Do not allow plugin uploads to be toggled through the API
	cfg.PluginSettings.EnableUploads = appCfg.PluginSettings.EnableUploads

	if cfg.MessageExportSettings.EnableExport != nil {
		c.App.HandleMessageExportConfig(cfg, appCfg)
	}

	updatedCfg, mergeErr := config.Merge(appCfg, cfg, &utils.MergeConfig{
		StructFieldFilter: filterFn,
	})

	if mergeErr != nil {
		c.Err = model.NewAppError("patchConfig", "api.config.update_config.restricted_merge.app_error", nil, mergeErr.Error(), http.StatusInternalServerError)
		return
	}

	err := updatedCfg.IsValid()
	if err != nil {
		c.Err = err
		return
	}

	err = c.App.SaveConfig(updatedCfg, true)
	if err != nil {
		c.Err = err
		return
	}

	auditRec.Success()

	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
	w.Write([]byte(c.App.GetSanitizedConfig().ToJson()))
}