# Dice Rolling — Design Spec

## Overview

Add a complete dice rolling system: server-side roll engine, shared real-time roll log panel, character sheet roll buttons for ability checks and attacks, advantage/disadvantage support, and a general-purpose dice roller.

## 1. Roll Engine (Server-Side)

### Socket.IO Events

**Client → Server:**

- `roll:request` — `{ campaignId, characterId?, characterName?, type, dice, label, modifier?, advantage?, disadvantage? }`
  - `type`: `'attack'` | `'ability-check'` | `'custom'`
  - `dice`: string expression like `'1d20'`, `'2d6'`, `'1d8+1'`
  - `label`: human-readable description (e.g. "SHORTSWORD attack", "DEX check", "2d6")
  - `modifier`: optional numeric modifier already included in the expression for display purposes
  - `advantage`/`disadvantage`: boolean, only meaningful for d20 rolls

**Server → Campaign Room:**

- `roll:result` — `{ id, campaignId, characterId, characterName, type, label, diceExpression, rolls, modifier, total, advantage, disadvantage, created_at }`
  - `rolls`: array of individual die results (e.g. `[14]` or `[14, 8]` for advantage)
  - `total`: final computed result

### Dice Expression Parser

Server-side parser that handles: `NdX`, `NdX+M`, `NdX-M`

- `N` = number of dice (default 1 if omitted, e.g. "d20" = "1d20")
- `X` = die size (4, 6, 8, 10, 12, 20, 100)
- `M` = optional flat modifier

Examples: `1d20`, `2d6`, `1d8+1`, `d20-1`, `4d6`, `1d100`

Invalid expressions return an error result with `{ error: "Couldn't parse: xyz" }`.

### Advantage / Disadvantage

For any roll where `advantage` or `disadvantage` is true:

- Roll the primary die (d20) twice instead of once
- `rolls` array contains both results: `[14, 8]`
- `total` uses the higher (advantage) or lower (disadvantage) of the two, plus modifier
- Display shows both dice with the chosen one highlighted

### roll_log Table

| Column          | Type    | Notes                               |
| --------------- | ------- | ----------------------------------- |
| id              | INTEGER | Primary key, autoincrement          |
| campaign_id     | INTEGER | FK to campaigns                     |
| character_id    | INTEGER | Nullable (null for anonymous rolls) |
| character_name  | TEXT    | Display name (or "Roll")            |
| type            | TEXT    | attack / ability-check / custom     |
| label           | TEXT    | Human-readable description          |
| dice_expression | TEXT    | Original expression (e.g. "1d20")   |
| rolls           | TEXT    | JSON array of die results           |
| modifier        | INTEGER | Flat modifier applied               |
| total           | INTEGER | Final result                        |
| advantage       | INTEGER | 0 or 1                              |
| disadvantage    | INTEGER | 0 or 1                              |
| created_at      | TEXT    | ISO timestamp                       |

## 2. Roll Log Panel

### Layout

Collapsible side panel on the right of the campaign view (outside the character modal).

- **Width:** ~300px on desktop
- **Mobile:** full-width bottom drawer
- **Collapsed state:** thin strip (~40px) with a dice icon and the last roll result visible. Click to expand.
- **Expanded state:** full panel with header, input, and scrollable log

### Panel Contents (top to bottom)

1. **Header:** "Roll Log" title + collapse button
2. **General roller input:** text input accepting dice expressions. Placeholder: "Roll dice... (e.g. 2d6+1)". Enter to roll. Rolls are anonymous (characterName = "Roll").
3. **Roll entries:** scrollable list, newest at top. Last ~50 loaded from DB on campaign entry.

### Roll Entry Card

Each roll displays as a small styled card:

- **Top line:** character name (bold, colored) + relative timestamp ("just now", "2m ago")
- **Label:** what was rolled ("SHORTSWORD attack", "DEX check", "2d6+1")
- **Dice breakdown:**
  - Normal: `d20: [14]`
  - With advantage: `d20: [14, 8] → 14` (higher highlighted)
  - With disadvantage: `d20: [14, 8] → 8` (lower highlighted)
  - Multiple dice: `2d6: [3, 5] = 8`
- **Modifier line** (if any): `+ STR (+0)`
- **Total:** large, bold, highlighted number
- **Pop-in animation:** new cards slide in and briefly highlight when they arrive

### Persistence

- Rolls saved to `roll_log` table
- On entering a campaign, load last 50 rolls via `GET /api/campaigns/:id/rolls`
- New rolls arrive in real-time via Socket.IO

## 3. Roll Buttons on Character Sheet

Roll buttons appear in **view mode only** (not edit mode).

### Ability Score Rolls

Each stat row in the StatsPanel gets a small dice button (🎲 or a styled button) on the right side (in the reserved rollSpace area).

- Click: rolls `1d20 + stat modifier`
- Label: "STR check", "DEX check", etc.
- Shift+click: advantage (rolls 2d20, takes higher)
- Ctrl/Cmd+click: disadvantage (rolls 2d20, takes lower)

### Attack Rolls

Each attack line in AttackBlock gets a dice button on the right side.

- Click: rolls `1d20 + attack modifier` for the hit, then rolls the weapon's damage die. Two entries appear in the log: attack roll, then damage roll.
- Label: "SHORTSWORD attack" for the d20, "SHORTSWORD damage" for the damage die
- Shift+click: advantage on the attack roll (damage is always normal)
- Ctrl/Cmd+click: disadvantage on the attack roll

### Keyboard Modifier Hint

A small hint text at the bottom of the StatsPanel or in the roll log panel header: "Shift: advantage · Ctrl: disadvantage"

## 4. Data Flow

1. Player clicks a roll button or types in the general roller
2. Client emits `roll:request` via Socket.IO with campaign ID, character info (if from sheet), dice expression, and advantage/disadvantage flags
3. Server parses the expression, generates random results, computes total
4. Server saves to `roll_log` table
5. Server broadcasts `roll:result` to the campaign room
6. All clients in the room receive the result and prepend it to their roll log
7. The new entry animates in with a pop-in effect

## 5. API Endpoints

- `GET /api/campaigns/:id/rolls` — returns last 50 rolls for a campaign, newest first
- Socket.IO handles all roll creation (no REST POST needed)

## 6. New/Modified Files

**Server:**

- `server/src/dice.ts` — dice expression parser + roller
- `server/src/routes/rolls.ts` — GET endpoint for roll history
- `server/src/db.ts` — add roll_log table
- `server/src/socket.ts` — handle roll:request, generate result, broadcast
- `server/src/index.ts` — register rolls route

**Client:**

- `client/src/components/RollLog.tsx` — the side panel component
- `client/src/components/RollLog.module.css` — panel styling
- `client/src/components/RollEntry.tsx` — individual roll result card
- `client/src/components/RollEntry.module.css` — card styling + animation
- `client/src/components/DiceButton.tsx` — small reusable dice roll button
- `client/src/components/DiceButton.module.css` — button styling
- `client/src/components/StatsPanel.tsx` — add DiceButton to each stat row
- `client/src/components/AttackBlock.tsx` — add DiceButton to each attack line
- `client/src/pages/CampaignView.tsx` — add RollLog panel, handle roll socket events
- `client/src/pages/CampaignView.module.css` — adjust layout for side panel
- `client/src/types.ts` — add RollResult type

## Out of Scope

- Animated 3D dice (future enhancement)
- "Roll as" character/NPC selector for general roller (future)
- "Drop lowest" or complex dice expressions
- Talent effects modifying rolls automatically
- Sound effects
