package systemstatusapi

import (
	"context"
	"encoding/json"
	"github.com/itworx/pulse/internal/problem"
	"github.com/itworx/pulse/internal/systemstatus"
	"net/http"
	"runtime"
)

type Handler struct {
	Snapshot    func(context.Context) (systemstatus.Snapshot, error)
	Diagnostics func(context.Context) (Diagnostics, error)
}

type Diagnostics struct {
	Status  systemstatus.Snapshot `json:"status"`
	Config  ConfigSummary         `json:"config"`
	Runtime RuntimeSummary        `json:"runtime"`
	Metrics string                `json:"metrics"`
}

type ConfigSummary struct {
	Environment          string `json:"environment"`
	Timezone             string `json:"timezone"`
	Locale               string `json:"locale"`
	AuthMode             string `json:"authMode"`
	PublicURLConfigured  bool   `json:"publicUrlConfigured"`
	DatabaseConfigured   bool   `json:"databaseConfigured"`
	PrometheusConfigured bool   `json:"prometheusConfigured"`
	UnraidConfigured     bool   `json:"unraidConfigured"`
	OIDCConfigured       bool   `json:"oidcConfigured"`
}

type RuntimeSummary struct {
	Goroutines int    `json:"goroutines"`
	GoVersion  string `json:"goVersion"`
}

func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		problem.Write(w, r, http.StatusMethodNotAllowed, "METHOD_NOT_ALLOWED", "Method not allowed", "Only GET is supported.", nil)
		return
	}
	var value any
	var err error
	switch r.URL.Path {
	case "/api/v1/system/status":
		if h.Snapshot == nil {
			err = http.ErrServerClosed
		} else {
			value, err = h.Snapshot(r.Context())
		}
	case "/api/v1/system/diagnostics":
		if h.Diagnostics == nil {
			err = http.ErrServerClosed
		} else {
			value, err = h.Diagnostics(r.Context())
		}
	default:
		http.NotFound(w, r)
		return
	}
	if err != nil {
		problem.Write(w, r, http.StatusServiceUnavailable, "STATUS_UNAVAILABLE", "Status unavailable", "The system status could not be read.", nil)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Cache-Control", "private, no-store")
	_ = json.NewEncoder(w).Encode(value)
}

func Runtime() RuntimeSummary {
	return RuntimeSummary{Goroutines: runtime.NumGoroutine(), GoVersion: runtime.Version()}
}