import { numericGridSize, seededRandom } from './caRuntime.js'
import type { CaClass, JsonObject, SceneParams } from './types.js'

export interface InitialConditionResult {
  type: 'cells'
  cells: number[][]
  generator: {
    kind: string
  } & JsonObject
}

export interface InitialConditionRuntimeInput {
  settings: SceneParams
  caClass: CaClass
  params: JsonObject
}

export interface InitialConditionRuntime {
  id: string
  label: string
  generate: (input: InitialConditionRuntimeInput) => InitialConditionResult
}

const initialConditionRuntimes = new Map<string, InitialConditionRuntime>()

function clampDensity(value: unknown) {
  return Math.max(0, Math.min(1, typeof value === 'number' ? value : 0.28))
}

function randomSoup({ settings, caClass, params }: InitialConditionRuntimeInput): InitialConditionResult {
  const density = clampDensity(params.density)
  const seed = typeof params.seed === 'string' ? params.seed : 'studio-seed'
  const random = seededRandom(seed)
  const [width, height, depth] = numericGridSize(settings.simulation?.grid, caClass.dimensions)
  const cells: number[][] = []

  for (let z = 0; z < depth; z += 1) {
    for (let y = 0; y < height; y += 1) {
      for (let x = 0; x < width; x += 1) {
        if (random() < density) cells.push([x, y, z])
      }
    }
  }

  return {
    type: 'cells',
    cells,
    generator: {
      kind: 'random-soup',
      density,
      seed
    }
  }
}

export function registerInitialConditionRuntime(
  runtime: InitialConditionRuntime,
  options: { replace?: boolean } = {}
) {
  if (!runtime.id.trim()) throw new Error('Initial condition runtime id is required')
  if (initialConditionRuntimes.has(runtime.id) && !options.replace) {
    throw new Error(`Initial condition runtime already registered: ${runtime.id}`)
  }
  initialConditionRuntimes.set(runtime.id, runtime)
}

export function listInitialConditionRuntimes() {
  return [...initialConditionRuntimes.values()]
}

export function getInitialConditionRuntime(runtimeId: string) {
  return initialConditionRuntimes.get(runtimeId) ?? null
}

export function generateInitialCondition(runtimeId: string, input: InitialConditionRuntimeInput) {
  const runtime = getInitialConditionRuntime(runtimeId)
  if (!runtime) throw new Error(`Initial condition runtime unavailable: ${runtimeId}`)

  const result = runtime.generate(input)
  if (result.type !== 'cells' || !Array.isArray(result.cells)) {
    throw new Error(`Initial condition runtime returned an invalid result: ${runtimeId}`)
  }
  return result
}

registerInitialConditionRuntime(
  {
    id: 'random-soup',
    label: 'Random soup',
    generate: randomSoup
  },
  { replace: true }
)