package handlers

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"net/http"

	"aamos-admin/models"
)

type DashboardResponse struct {
	UsersCount     int                    `json:"users_count"`
	ModulesHealthy int                    `json:"modules_healthy"`
	ModulesTotal   int                    `json:"modules_total"`
	RecentAudit    []models.AuditLog      `json:"recent_audit"`
	SystemMetrics  DashboardSystemMetrics `json:"system_metrics"`
}

type DashboardSystemMetrics struct {
	CPU  CPUMetrics  `json:"cpu"`
	RAM  RAMMetrics  `json:"ram"`
	Disk DiskMetrics `json:"disk"`
}

func DashboardHandler(db *sql.DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		var usersCount int
		if err := db.QueryRowContext(r.Context(), `SELECT COUNT(*) FROM users`).Scan(&usersCount); err != nil {
			http.Error(w, fmt.Sprintf("db error: %v", err), http.StatusInternalServerError)
			return
		}

		var modulesTotal, modulesHealthy int
		if err := db.QueryRowContext(r.Context(), `SELECT COUNT(*) FROM modules`).Scan(&modulesTotal); err != nil {
			http.Error(w, fmt.Sprintf("db error: %v", err), http.StatusInternalServerError)
			return
		}
		if err := db.QueryRowContext(r.Context(),
			`SELECT COUNT(*) FROM modules WHERE status = $1`, string(models.ModuleStatusRunning),
		).Scan(&modulesHealthy); err != nil {
			http.Error(w, fmt.Sprintf("db error: %v", err), http.StatusInternalServerError)
			return
		}

		rows, err := db.QueryContext(r.Context(), `
			SELECT id, user_id, action, resource, ip, timestamp, details
			FROM audit_logs
			ORDER BY timestamp DESC
			LIMIT 5
		`)
		if err != nil {
			http.Error(w, fmt.Sprintf("db error: %v", err), http.StatusInternalServerError)
			return
		}
		defer rows.Close()

		audit := make([]models.AuditLog, 0, 5)
		for rows.Next() {
			var a models.AuditLog
			if err := rows.Scan(&a.ID, &a.UserID, &a.Action, &a.Resource, &a.IP, &a.Timestamp, &a.Details); err != nil {
				http.Error(w, fmt.Sprintf("scan error: %v", err), http.StatusInternalServerError)
				return
			}
			audit = append(audit, a)
		}
		if err := rows.Err(); err != nil {
			http.Error(w, fmt.Sprintf("rows error: %v", err), http.StatusInternalServerError)
			return
		}

		cpu, err := readCPU()
		if err != nil {
			http.Error(w, fmt.Sprintf("cpu read error: %v", err), http.StatusInternalServerError)
			return
		}
		ram, err := readRAM()
		if err != nil {
			http.Error(w, fmt.Sprintf("ram read error: %v", err), http.StatusInternalServerError)
			return
		}
		disk, err := readDisk("/")
		if err != nil {
			http.Error(w, fmt.Sprintf("disk read error: %v", err), http.StatusInternalServerError)
			return
		}

		resp := DashboardResponse{
			UsersCount:     usersCount,
			ModulesHealthy: modulesHealthy,
			ModulesTotal:   modulesTotal,
			RecentAudit:    audit,
			SystemMetrics: DashboardSystemMetrics{
				CPU:  cpu,
				RAM:  ram,
				Disk: disk,
			},
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(resp)
	}
}