package server

import (
	"net/http"
	"sync"

	"github.com/google/uuid"
)

// GCLastRun records the result of the last GC run.
type GCLastRun struct {
	StartedAt    string `json:"started_at"`
	CompletedAt  string `json:"completed_at,omitempty"`
	BlobsRemoved int    `json:"blobs_removed"`
	BytesFreed   int64  `json:"bytes_freed"`
}

// GCState tracks the current state of garbage collection.
type GCState struct {
	mu      sync.Mutex
	Running bool       `json:"running"`
	LastRun *GCLastRun `json:"last_run,omitempty"`
}

type gcStatusResponse struct {
	Running bool       `json:"running"`
	LastRun *GCLastRun `json:"last_run,omitempty"`
}

type gcTriggerResponse struct {
	ID string `json:"id"`
}

// AdminTriggerGCHandler handles POST /v1/gc.
func AdminTriggerGCHandler(state *GCState) http.HandlerFunc {
	return func(w http.ResponseWriter, _ *http.Request) {
		state.mu.Lock()
		if state.Running {
			state.mu.Unlock()
			writeAdminError(w, http.StatusConflict, "garbage collection already running")
			return
		}
		state.Running = true
		state.mu.Unlock()

		// GC engine is Phase 9 -- for now, just mark as running and return.
		// The actual GC goroutine will be wired up in Phase 9.
		gcID := uuid.New().String()

		writeJSON(w, http.StatusAccepted, gcTriggerResponse{ID: gcID})
	}
}

// AdminGCStatusHandler handles GET /v1/gc/status.
func AdminGCStatusHandler(state *GCState) http.HandlerFunc {
	return func(w http.ResponseWriter, _ *http.Request) {
		state.mu.Lock()
		resp := gcStatusResponse{
			Running: state.Running,
			LastRun: state.LastRun,
		}
		state.mu.Unlock()

		writeJSON(w, http.StatusOK, resp)
	}
}