Crussell/backend/handlers/scheduling/time-blockers.go

package scheduling

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

	"crussell/db"
	"crussell/mw"

	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5"
)

// --- Types ---

type TimeBlocker struct {
	ID              string     `json:"id"`
	StartTime       time.Time  `json:"start_time"`
	DurationMinutes int        `json:"duration_minutes"`
	Description     string     `json:"description,omitempty"`
	CronExpression  *string    `json:"cron_expression,omitempty"`
	CreatedAt       time.Time  `json:"created_at"`
	CreatedBy       *string    `json:"created_by,omitempty"`
}

type CreateTimeBlockerRequest struct {
	StartTime       time.Time  `json:"start_time"`
	DurationMinutes int        `json:"duration_minutes"`
	Description     string     `json:"description,omitempty"`
	CronExpression  *string    `json:"cron_expression,omitempty"`
}

// --- List Time Blockers ---
// GET /api/admin/time-blockers
func ListTimeBlockers(w http.ResponseWriter, r *http.Request) {
	// Optional date range filtering
	startStr := r.URL.Query().Get("start")
	endStr := r.URL.Query().Get("end")

	var rows pgx.Rows
	var err error

	if startStr != "" && endStr != "" {
		// Filter by date range
		ukLocation, _ := time.LoadLocation("Europe/London")
		start, err1 := time.ParseInLocation("2006-01-02", startStr, ukLocation)
		end, err2 := time.ParseInLocation("2006-01-02", endStr, ukLocation)
		if err1 != nil || err2 != nil {
			http.Error(w, "invalid date format, expected YYYY-MM-DD", http.StatusBadRequest)
			return
		}
		start = time.Date(start.Year(), start.Month(), start.Day(), 0, 0, 0, 0, ukLocation)
		end = time.Date(end.Year(), end.Month(), end.Day(), 23, 59, 59, 999999999, ukLocation)

		rows, err = db.DB.Query(r.Context(), `
			SELECT id, start_time, duration_minutes, description, cron_expression, created_at, created_by
			FROM time_blockers
			WHERE start_time >= $1 AND start_time <= $2
			ORDER BY start_time DESC
		`, start, end)
	} else {
		// Get all blockers (most recent first, limited)
		rows, err = db.DB.Query(r.Context(), `
			SELECT id, start_time, duration_minutes, description, cron_expression, created_at, created_by
			FROM time_blockers
			ORDER BY start_time DESC
			LIMIT 100
		`)
	}

	if err != nil {
		http.Error(w, "failed to fetch time blockers", http.StatusInternalServerError)
		return
	}
	defer rows.Close()

	var blockers []TimeBlocker
	for rows.Next() {
		var b TimeBlocker
		if err := rows.Scan(&b.ID, &b.StartTime, &b.DurationMinutes, &b.Description, &b.CronExpression, &b.CreatedAt, &b.CreatedBy); err != nil {
			http.Error(w, "failed to scan time blocker", http.StatusInternalServerError)
			return
		}
		blockers = append(blockers, b)
	}

	if err := rows.Err(); err != nil {
		http.Error(w, "error iterating time blockers", http.StatusInternalServerError)
		return
	}

	if blockers == nil {
		blockers = []TimeBlocker{}
	}

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

// --- Create Time Blocker ---
// POST /api/admin/time-blockers
func CreateTimeBlocker(w http.ResponseWriter, r *http.Request) {
	var req CreateTimeBlockerRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "invalid JSON: "+err.Error(), http.StatusBadRequest)
		return
	}

	// Validate required fields
	if req.StartTime.IsZero() {
		http.Error(w, "start_time is required", http.StatusBadRequest)
		return
	}
	if req.DurationMinutes <= 0 {
		http.Error(w, "duration_minutes must be greater than 0", http.StatusBadRequest)
		return
	}

	// Get admin user ID from context
	var createdBy *string
	if userID, ok := r.Context().Value(mw.UserIDKey).(string); ok {
		createdBy = &userID
	}

	// Insert the time blocker
	var blocker TimeBlocker
	err := db.DB.QueryRow(r.Context(), `
		INSERT INTO time_blockers (start_time, duration_minutes, description, cron_expression, created_by)
		VALUES ($1, $2, $3, $4, $5)
		RETURNING id, start_time, duration_minutes, description, cron_expression, created_at, created_by
	`, req.StartTime, req.DurationMinutes, req.Description, req.CronExpression, createdBy).Scan(
		&blocker.ID, &blocker.StartTime, &blocker.DurationMinutes, &blocker.Description,
		&blocker.CronExpression, &blocker.CreatedAt, &blocker.CreatedBy,
	)
	if err != nil {
		http.Error(w, "failed to create time blocker", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(blocker)
}

// --- Delete Time Blocker ---
// DELETE /api/admin/time-blockers/{id}
func DeleteTimeBlocker(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	if id == "" {
		http.Error(w, "missing id parameter", http.StatusBadRequest)
		return
	}

	result, err := db.DB.Exec(r.Context(), `
		DELETE FROM time_blockers WHERE id = $1
	`, id)
	if err != nil {
		http.Error(w, "failed to delete time blocker", http.StatusInternalServerError)
		return
	}

	rowsAffected := result.RowsAffected()
	if rowsAffected == 0 {
		http.Error(w, "time blocker not found", http.StatusNotFound)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// --- Helper: Check Time Blocker Overlap ---
// Returns (hasOverlap, blockerDescription, error)
// Used by booking handlers to check for blocker conflicts
func CheckTimeBlockerOverlap(ctx context.Context, startTime, endTime time.Time) (bool, string, error) {
	var description string
	var hasOverlap bool

	err := db.DB.QueryRow(ctx, `
		SELECT EXISTS (
			SELECT 1 FROM time_blockers
			WHERE start_time < $2
			AND start_time + (INTERVAL '1 minute' * duration_minutes) > $1
		)
	`, startTime, endTime).Scan(&hasOverlap)

	if err != nil {
		return false, "", err
	}

	if hasOverlap {
		// Get the description of the overlapping blocker
		db.DB.QueryRow(ctx, `
			SELECT COALESCE(description, 'Time blocked')
			FROM time_blockers
			WHERE start_time < $2
			AND start_time + (INTERVAL '1 minute' * duration_minutes) > $1
			LIMIT 1
		`, startTime, endTime).Scan(&description)
	}

	return hasOverlap, description, nil
}

// --- Helper: Get Time Blockers in Range ---
// Returns blockers for the given date range, expanded for recurring blockers
// Used by GetAvailableHours to subtract blocked time from available slots
func GetTimeBlockersInRange(ctx context.Context, start, end time.Time) ([]TimeBlocker, error) {
	// For now, only return one-off blockers (cron_expression IS NULL)
	// TODO: Implement cron expansion for recurring blockers
	rows, err := db.DB.Query(ctx, `
		SELECT id, start_time, duration_minutes, description, cron_expression, created_at, created_by
		FROM time_blockers
		WHERE cron_expression IS NULL
		AND start_time >= $1 AND start_time <= $2
		ORDER BY start_time
	`, start, end)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var blockers []TimeBlocker
	for rows.Next() {
		var b TimeBlocker
		if err := rows.Scan(&b.ID, &b.StartTime, &b.DurationMinutes, &b.Description, &b.CronExpression, &b.CreatedAt, &b.CreatedBy); err != nil {
			return nil, err
		}
		blockers = append(blockers, b)
	}

	return blockers, rows.Err()
}