package applicationapi

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"strings"
	"time"

	"github.com/itworx/pulse/internal/application"
	"github.com/itworx/pulse/internal/auth"
	"github.com/itworx/pulse/internal/problem"
)

type Handler struct {
	Provider interface {
		Snapshot(context.Context) (application.Snapshot, error)
	}
}

func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet || (r.URL.Path != "/api/v1/applications" && !strings.HasPrefix(r.URL.Path, "/api/v1/applications/")) {
		http.NotFound(w, r)
		return
	}
	if _, ok := auth.PrincipalFromContext(r.Context()); !ok {
		problem.Write(w, r, http.StatusUnauthorized, "UNAUTHORIZED", "Authentication required", "Authentication is required to read applications.", nil)
		return
	}
	snapshot, err := h.snapshot(r)
	if err != nil {
		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
			return
		}
		problem.Write(w, r, http.StatusServiceUnavailable, "APPLICATIONS_UNAVAILABLE", "Applications not available", "Applicatiegegevens konden niet worden gelezen.", nil)
		return
	}
	if r.URL.Path != "/api/v1/applications" {
		id := strings.TrimPrefix(r.URL.Path, "/api/v1/applications/")
		for _, item := range snapshot.Applications {
			if item.ID == id {
				writeJSON(w, struct {
					Source      application.Source      `json:"source"`
					Application application.Application `json:"application"`
				}{Source: snapshot.Source, Application: item})
				return
			}
		}
		http.NotFound(w, r)
		return
	}
	if len(snapshot.Applications) > 100 {
		snapshot.Applications = snapshot.Applications[:100]
	}
	writeJSON(w, snapshot)
}
func (h Handler) snapshot(r *http.Request) (application.Snapshot, error) {
	if h.Provider == nil {
		return application.UnknownSnapshot(time.Now().UTC(), "applications", "agent", "source_unavailable"), nil
	}
	return h.Provider.Snapshot(r.Context())
}
func writeJSON(w http.ResponseWriter, value any) {
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Cache-Control", "private, max-age=5")
	_ = json.NewEncoder(w).Encode(value)
}