root
49 lines
1.3 KiB
Go
49 lines
1.3 KiB
Go
// Package market prices ore and settles deliveries. Prices are integers
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// (credits per kg) that fall as supply accumulates and recover over time.
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package market
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import "wh/world"
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var basePrice = [world.NumOre]int64{world.Iron: 2, world.Nickel: 6, world.Ice: 3, world.Platinum: 300}
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// saturation is the supply (kg) at which an ore's price has halved.
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var saturation = [world.NumOre]int64{world.Iron: 400_000, world.Nickel: 200_000, world.Ice: 300_000, world.Platinum: 5_000}
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type Market struct {
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Supply [world.NumOre]int64 // decayed running total of kg sold
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Prices [world.NumOre]int64 // credits per kg, fixed for the day
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}
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func New() Market {
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m := Market{}
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m.reprice()
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return m
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}
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func (m *Market) reprice() {
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for o := range m.Prices {
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p := basePrice[o] * saturation[o] / (saturation[o] + m.Supply[o])
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if p < 1 {
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p = 1
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}
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m.Prices[o] = p
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}
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}
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// Value returns the payout for a cargo at today's prices.
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func (m *Market) Value(cargo [world.NumOre]int64) int64 {
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var v int64
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for o, kg := range cargo {
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v += kg * m.Prices[o]
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}
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return v
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}
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// EndOfDay folds the day's sales into supply (with 10% decay) and reprices.
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func (m *Market) EndOfDay(sold [world.NumOre]int64) {
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for o := range m.Supply {
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m.Supply[o] = m.Supply[o]*9/10 + sold[o]
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}
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m.reprice()
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}
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