feast/src/game/combat.ts

import { Creature, POV } from './entity'
import { POVActionPicker } from './language'
import { Container } from './vore'
import { LogEntry, LogLines, CompositeLog } from './interface'

export enum DamageType {Pierce, Slash, Crush, Acid}

export interface DamageInstance {
    type: DamageType;
    amount: number;
}

export class Damage {
    readonly damages: DamageInstance[]

    constructor (...damages: DamageInstance[]) {
      this.damages = damages
    }

    scale (factor: number): Damage {
      const results: Array<DamageInstance> = []

      this.damages.forEach(damage => {
        results.push({
          type: damage.type,
          amount: damage.amount * factor
        })
      })

      return new Damage(...results)
    }
}

export enum Stat {
    STR = 'Strength',
    DEX = 'Dexterity',
    CON = 'Constitution'
}

export type Stats = {[key in Stat]: number}

export enum State {
    Normal = 'Normal',
    Grappled = 'Grappled',
    Grappling = 'Grappling',
    Eaten = 'Eaten'
}

export interface Combatant {
    actions: Array<Action>;
}

export abstract class Action {
  public name: string;
  allowed (user: Creature, target: Creature) {
    return this.userStates.has(user.state) && this.targetStates.has(target.state)
  }

    abstract execute(user: Creature, target: Creature): LogEntry

    constructor (name: string, public userStates: Set<State>, public targetStates: Set<State>) {
      this.name = name
    }

    toString (): string {
      return this.name
    }
}

abstract class SelfAction extends Action {
  allowed (user: Creature, target: Creature) {
    if (user === target) {
      return super.allowed(user, target)
    } else {
      return false
    }
  }
}

abstract class PairAction extends Action {
  allowed (user: Creature, target: Creature) {
    if (user !== target) {
      return super.allowed(user, target)
    } else {
      return false
    }
  }
}

export class AttackAction extends PairAction {
    protected lines: POVActionPicker = {
      [POV.First]: {
        [POV.First]: (user, target) => new LogLines('You bite...yourself?'),
        [POV.Third]: (user, target) => new LogLines('You bite ' + target.name)
      },
      [POV.Third]: {
        [POV.First]: (user, target) => new LogLines(user.name.capital + ' bites you'),
        [POV.Third]: (user, target) => new LogLines(user.name.capital + ' bites ' + target.name)
      }
    }

    constructor (protected damage: Damage) {
      super('Attack', new Set([State.Normal]), new Set([State.Normal]))
    }

    execute (user: Creature, target: Creature): LogEntry {
      target.takeDamage(this.damage)
      return this.lines[user.perspective][target.perspective](user, target)
    }
}

export class DevourAction extends PairAction {
    protected lines: POVActionPicker = {
      [POV.First]: {
        [POV.First]: (user, target) => new LogLines('You devour...yourself?'),
        [POV.Third]: (user, target) => new LogLines('You devour ' + target.name)
      },
      [POV.Third]: {
        [POV.First]: (user, target) => new LogLines(user.name.capital + ' devours you'),
        [POV.Third]: (user, target) => new LogLines(user.name.capital + ' devours ' + target.name)
      }
    }

    constructor (protected container: Container) {
      super('Devour', new Set([State.Normal]), new Set([State.Normal]))
    }

    execute (user: Creature, target: Creature): LogEntry {
      target.state = State.Eaten
      return new CompositeLog(this.lines[user.perspective][target.perspective](user, target), this.container.consume(target))
    }
}

export class StruggleAction extends PairAction {
    protected lines: POVActionPicker = {
      [POV.First]: {
        [POV.First]: (user, target) => new LogLines('You escape from...yourself?'),
        [POV.Third]: (user, target) => new LogLines('You escape from ' + target.name)
      },
      [POV.Third]: {
        [POV.First]: (user, target) => new LogLines(user.name.capital + ' escapes from you'),
        [POV.Third]: (user, target) => new LogLines(user.name.capital + ' escapes from ' + target.name)
      }
    }

    constructor () {
      super('Struggle', new Set([State.Eaten]), new Set([State.Normal]))
    }

    execute (user: Creature, target: Creature): LogEntry {
      if (user.containedIn) {
        user.state = State.Normal
        return new CompositeLog(this.lines[user.perspective][target.perspective](user, target), user.containedIn.release(user))
      } else { return new LogLines("The prey wasn't actually eaten...") }
    }
}

export class DigestAction extends SelfAction {
    protected lines: POVActionPicker = {
      [POV.First]: {
        [POV.First]: (user, target) => new LogLines('You rub your stomach'),
        [POV.Third]: (user, target) => new LogLines("You can't digest for other people...")
      },
      [POV.Third]: {
        [POV.First]: (user, target) => new LogLines("Other people can't digest for you..."),
        [POV.Third]: (user, target) => new LogLines(user.name.capital + ' rubs ' + user.pronouns.possessive + ' gut.')
      }
    }

    allowed (user: Creature, target: Creature) {
      if (Array.from(user.containers).some(container => {
        return container.contents.size > 0
      })) {
        return super.allowed(user, target)
      } else {
        return false
      }
    }

    constructor () {
      super('Digest', new Set([State.Normal]), new Set([State.Normal]))
    }

    execute (user: Creature, target: Creature): LogEntry {
      const results = new CompositeLog(...Array.from(user.containers).map(container => container.tick(60)))
      return new CompositeLog(this.lines[user.perspective][target.perspective](user, target), results)
    }
}

export interface CombatTest {
    test: (user: Creature, target: Creature) => boolean;
    odds: (user: Creature, target: Creature) => number;
    explain: (user: Creature, target: Creature) => LogEntry;
}

function logistic (x0: number, L: number, k: number): (x: number) => number {
  return (x: number) => {
    return L / (1 + Math.exp(-k * (x - x0)))
  }
}

abstract class RandomTest implements CombatTest {
  test (user: Creature, target: Creature): boolean {
    return Math.random() < this.odds(user, target)
  }

    abstract odds(user: Creature, target: Creature): number
    abstract explain(user: Creature, target: Creature): LogEntry
}

export class StatTest extends RandomTest {
    private f: (x: number) => number

    constructor (public readonly stat: Stat, k = 0.1) {
      super()
      this.f = logistic(0, 1, k)
    }

    odds (user: Creature, target: Creature): number {
      return this.f(user.stats[this.stat] - target.stats[this.stat])
    }

    explain (user: Creature, target: Creature): LogEntry {
      const delta: number = user.stats[this.stat] - target.stats[this.stat]
      let result: string

      if (delta === 0) {
        result = 'You and the target have the same ' + this.stat + '.'
      } else if (delta < 0) {
        result = 'You have ' + delta + ' less ' + this.stat + ' than your foe.'
      } else {
        result = 'You have ' + delta + ' more ' + this.stat + ' than you foe.'
      }

      result += ' Your odds of success are ' + (100 * this.odds(user, target)) + '%'

      return new LogLines(result)
    }
}

export class ChanceTest extends RandomTest {
  constructor (public readonly chance: number) {
    super()
  }

  odds (user: Creature, target: Creature): number {
    return this.chance
  }

  explain (user: Creature, target: Creature): LogEntry {
    return new LogLines('You have a flat ' + (100 * this.chance) + '% chance.')
  }
}