package ec2simulation

import rand "math/rand"

type Simulation struct {
    max_instances uint // Maximum number of instances that may be started
    clock *Clock       // Simulation virtual time, starts at 0 and incremented by Tick()
    rand *rand.Rand    // Psuedo-random number generator. Seed may be fixed to allow deterministic results
    chunks []*Chunk
}

func NewSimulation(max_instances uint) *Simulation {
    sim := &Simulation{max_instances: max_instances}
    sim.clock = NewClock()
    sim.rand = rand.New(rand.NewSource(0))

    return sim
}

func (sim *Simulation) Run(duration uint) {
    for i := uint(0); i < duration; i++ {
        sim.step()
    }
}

func (sim *Simulation) AddChunks(count uint, duration_mean uint, duration_stddev float64) {
    for i := uint(0); i < count; i++ {
        // Create chunk with random duration specified by |duration_mean| and |duration_stddev|
        duration := uint(rand.NormFloat64() * duration_stddev + float64(duration_mean))
        sim.chunks = append(sim.chunks, NewChunk(sim.clock, duration))
    }
}


func (sim *Simulation) step() {
    sim.clock.Tick()
}