import fs from 'node:fs'
import path from 'node:path'

export type OccluderDefaultsSlot = 'baseline' | 'tuned'

type OccluderDefaults = {
  params: Record<string, number>
  occluderEnv: Record<string, number>
}

const PARAMS_FILE = path.resolve(process.cwd(), 'models', 'occluder', 'params.json')
const FALLBACK_DEFAULTS: Record<OccluderDefaultsSlot, OccluderDefaults> = {
  baseline: {
    params: {
      maskGrowPx: 8,
      maskPreBlur: 1,
      maskThresh: 0.4,
      maskFinalBlur: 2,
      occluderShrinkPx: 2,
      occluderEdgeTrimPx: 4,
      occluderLeakGuardPx: 2,
      tileFeatherPx: 0,
      occluderFeatherPx: 1,
    },
    occluderEnv: {
      OCCLUDER_SAM_MAX_LEAK: 0.2,
      OCCLUDER_SAM_LEAK_WEIGHT: 1.5,
      OCCLUDER_SAM_BAND_RADIUS: 8,
      OCCLUDER_SAM_NEG_ERODE: 1,
      OCCLUDER_SAM_POS_BAND_ONLY: 1,
      OCCLUDER_SAM_MIN_OVERLAP: 0.05,
      OCCLUDER_SAM_NEG_Q: 0.6,
      OCCLUDER_SAM_POS_GRAD_Q: 0.85,
      OCCLUDER_SAM_MIN_OUTSIDE: 0.005,
      OCCLUDER_SAM_BOX_MARGIN: 40,
      OCCLUDER_SAM_MAX_TILE_RATIO: 0.9,
      OCCLUDER_SAM_TOP_K: 1,
      OCCLUDER_SAM_EDGE_WEIGHT: 0.25,
      OCCLUDER_SAM_EDGE_RADIUS: 1,
      OCCLUDER_SAM_PATCH_FNS: 0,
    },
  },
  tuned: {
    params: {
      maskGrowPx: 8,
      maskPreBlur: 1,
      maskThresh: 0.4,
      maskFinalBlur: 2,
      occluderShrinkPx: 2,
      occluderEdgeTrimPx: 4,
      occluderLeakGuardPx: 2,
      tileFeatherPx: 0,
      occluderFeatherPx: 1,
    },
    occluderEnv: {
      OCCLUDER_SAM_MAX_LEAK: 0.2,
      OCCLUDER_SAM_LEAK_WEIGHT: 1.5,
      OCCLUDER_SAM_BAND_RADIUS: 8,
      OCCLUDER_SAM_NEG_ERODE: 1,
      OCCLUDER_SAM_POS_BAND_ONLY: 1,
      OCCLUDER_SAM_MIN_OVERLAP: 0.05,
      OCCLUDER_SAM_NEG_Q: 0.6,
      OCCLUDER_SAM_POS_GRAD_Q: 0.85,
      OCCLUDER_SAM_MIN_OUTSIDE: 0.005,
      OCCLUDER_SAM_BOX_MARGIN: 40,
      OCCLUDER_SAM_MAX_TILE_RATIO: 0.9,
      OCCLUDER_SAM_TOP_K: 1,
      OCCLUDER_SAM_EDGE_WEIGHT: 0.25,
      OCCLUDER_SAM_EDGE_RADIUS: 1,
      OCCLUDER_SAM_PATCH_FNS: 1,
    },
  },
}

let cached: Record<OccluderDefaultsSlot, OccluderDefaults> | null = null

function loadDefaultsFile(): Record<OccluderDefaultsSlot, OccluderDefaults> {
  if (cached) return cached
  try {
    const contents = fs.readFileSync(PARAMS_FILE, 'utf8')
    const parsed = JSON.parse(contents) as Partial<Record<OccluderDefaultsSlot, OccluderDefaults>>
    cached = {
      baseline: parsed.baseline ?? FALLBACK_DEFAULTS.baseline,
      tuned: parsed.tuned ?? FALLBACK_DEFAULTS.tuned,
    }
  } catch {
    cached = FALLBACK_DEFAULTS
  }
  return cached
}

export function resolveOccluderSlot(slot?: string): OccluderDefaultsSlot {
  return slot?.toLowerCase() === 'tuned' ? 'tuned' : 'baseline'
}

export function getOccluderDefaults(slot?: string): OccluderDefaults {
  const chosen = resolveOccluderSlot(slot)
  const defaults = loadDefaultsFile()
  return defaults[chosen] ?? defaults.baseline
}