Sports Field Price Calculation Skill

[!IMPORTANT] Current System Architecture: This project uses Supabase Edge Functions (Deno) for the LINE chatbot backend. The pricing logic is currently inlined in supabase/functions/create-booking/index.ts and mirrored in src/pages/admin/DashboardPage.tsx for the frontend.

This skill provides the definitive pricing logic for the football field reservation system.

1. Field Configuration & Base Rates

The prices differ based on the time of day, split at 18:00.

2. Calculation Logic & Rounding Rules

The system splits a booking into two segments: Pre-18:00 and Post-18:00.

The "Dual Rounding" Rule

To ensure prices sum up intuitively for 30-minute slots, each segment is calculated and rounded UP to the nearest 100 THB independently if it contains a fraction.

Formula:

1. •Calculate Pre-Cost: PreHours * PreRate
   • •If valid (>0) and not divisible by 100: Round UP to nearest 100.
2. •Calculate Post-Cost: PostHours * PostRate
   • •If valid (>0) and not divisible by 100: Round UP to nearest 100.
3. •Total: Round(PreCost + PostCost)

Example Calculation: Field 1 (17:30 - 18:30)

• •Time: 17:30 - 18:30 (1 Hour Total)
• •Segments:
  • •17:30 - 18:00 (30 mins = 0.5 hr) @ 500
  • •18:00 - 18:30 (30 mins = 0.5 hr) @ 700
• •Step 1 (Pre): 0.5 * 500 = 250 -> Round UP to 300
• •Step 2 (Post): 0.5 * 700 = 350 -> Round UP to 400
• •Step 3 (Total): 300 + 400 = 700 THB

Example Calculation: Field 1 (17:00 - 18:30)

• •Time: 17:00 - 18:30 (1.5 Hours)
• •Segments:
  • •17:00 - 18:00 (1.0 hr) @ 500
  • •18:00 - 18:30 (0.5 hr) @ 700
• •Step 1 (Pre): 1.0 * 500 = 500 (No rounding needed)
• •Step 2 (Post): 0.5 * 700 = 350 -> Round UP to 400
• •Step 3 (Total): 500 + 400 = 900 THB

3. Anti-Gaming Policy (Discounts)

To prevent users from gaming the system (e.g., booking expensive slots with coupons and then switching to cheap slots or shorter times):

• •Rule 1: Duration Shrink = Burn: If a booking's duration is reduced (e.g. 1.5h -> 1h), any existing discount is REMOVED.
• •Rule 2: Court Move = Safe: If a booking is moved to a different court or time, checking only the duration. If the duration is the same (or longer), the discount is PRESERVED, even if the new court is cheaper.

Implementation Snippet

function calculatePrice(fieldId: number, startTime: string, durationHours: number) {
    // ... calculate preHours and postHours ...

    let prePrice = preHours * prices.pre;
    let postPrice = postHours * prices.post;

    // Apply Rounding Rule: Both Pre and Post prices round UP to nearest 100
    if (prePrice > 0 && prePrice % 100 !== 0) {
        prePrice = Math.ceil(prePrice / 100) * 100;
    }
    if (postPrice > 0 && postPrice % 100 !== 0) {
        postPrice = Math.ceil(postPrice / 100) * 100;
    }

    return Math.round(prePrice + postPrice);
}

Supported Durations

• •1 Hour
• •1.5 Hours
• •2 Hours
• •(System supports any duration, practically limited by 30-min slots)