// Package handlers provides HTTP request handlers.
package handlers

import (
	"bytes"
	"encoding/json"
	"log/slog"
	"net/http"

	"github.com/gorilla/csrf"
	"go.uber.org/fx"

	"sneak.berlin/go/upaas/internal/database"
	"sneak.berlin/go/upaas/internal/docker"
	"sneak.berlin/go/upaas/internal/globals"
	"sneak.berlin/go/upaas/internal/healthcheck"
	"sneak.berlin/go/upaas/internal/logger"
	"sneak.berlin/go/upaas/internal/models"
	"sneak.berlin/go/upaas/internal/service/app"
	"sneak.berlin/go/upaas/internal/service/audit"
	"sneak.berlin/go/upaas/internal/service/auth"
	"sneak.berlin/go/upaas/internal/service/deploy"
	"sneak.berlin/go/upaas/internal/service/webhook"
	"sneak.berlin/go/upaas/templates"
)

// Params contains dependencies for Handlers.
type Params struct {
	fx.In

	Logger      *logger.Logger
	Globals     *globals.Globals
	Database    *database.Database
	Healthcheck *healthcheck.Healthcheck
	Auth        *auth.Service
	App         *app.Service
	Deploy      *deploy.Service
	Webhook     *webhook.Service
	Docker      *docker.Client
	Audit       *audit.Service
}

// Handlers provides HTTP request handlers.
type Handlers struct {
	log        *slog.Logger
	params     *Params
	db         *database.Database
	hc         *healthcheck.Healthcheck
	auth       *auth.Service
	appService *app.Service
	deploy     *deploy.Service
	webhook    *webhook.Service
	docker     *docker.Client
	audit      *audit.Service
	globals    *globals.Globals
}

// New creates a new Handlers instance.
func New(_ fx.Lifecycle, params Params) (*Handlers, error) {
	return &Handlers{
		log:        params.Logger.Get(),
		params:     &params,
		db:         params.Database,
		hc:         params.Healthcheck,
		auth:       params.Auth,
		appService: params.App,
		deploy:     params.Deploy,
		webhook:    params.Webhook,
		docker:     params.Docker,
		audit:      params.Audit,
		globals:    params.Globals,
	}, nil
}

// currentUser returns the currently authenticated user, or nil if not authenticated.
func (h *Handlers) currentUser(request *http.Request) *models.User {
	user, err := h.auth.GetCurrentUser(request.Context(), request)
	if err != nil || user == nil {
		return nil
	}

	return user
}

// auditLog records an audit entry for the current request.
func (h *Handlers) auditLog(
	request *http.Request,
	action models.AuditAction,
	resourceType models.AuditResourceType,
	resourceID string,
	detail string,
) {
	user := h.currentUser(request)

	entry := audit.LogEntry{
		Action:       action,
		ResourceType: resourceType,
		ResourceID:   resourceID,
		Detail:       detail,
	}

	if user != nil {
		entry.UserID = user.ID
		entry.Username = user.Username
	} else {
		entry.Username = "anonymous"
	}

	h.audit.LogFromRequest(request.Context(), request, entry)
}

// addGlobals adds version info and CSRF token to template data map.
func (h *Handlers) addGlobals(
	data map[string]any,
	request *http.Request,
) map[string]any {
	data["Version"] = h.globals.Version
	data["Appname"] = h.globals.Appname

	if request != nil {
		data["CSRFField"] = csrf.TemplateField(request)
	}

	return data
}

// renderTemplate executes the named template into a buffer first, then writes
// to the ResponseWriter only on success. This prevents partial/corrupt HTML
// responses when template execution fails partway through.
func (h *Handlers) renderTemplate(
	writer http.ResponseWriter,
	tmpl *templates.TemplateExecutor,
	name string,
	data any,
) {
	var buf bytes.Buffer

	err := tmpl.ExecuteTemplate(&buf, name, data)
	if err != nil {
		h.log.Error("template execution failed", "error", err)
		http.Error(writer, "Internal Server Error", http.StatusInternalServerError)

		return
	}

	_, _ = buf.WriteTo(writer)
}

func (h *Handlers) respondJSON(
	writer http.ResponseWriter,
	_ *http.Request,
	data any,
	status int,
) {
	writer.Header().Set("Content-Type", "application/json")
	writer.WriteHeader(status)

	if data != nil {
		err := json.NewEncoder(writer).Encode(data)
		if err != nil {
			h.log.Error("json encode error", "error", err)
		}
	}
}