// Static LOD gate: validates spatial cells, REPLACE hierarchy, nonempty content and LOD byte/triangle reduction.
import { readFileSync, statSync } from 'node:fs'
import { resolve, dirname, join } from 'node:path'
const dir = resolve(process.argv[2] || 'tools/city-massing/district/lod-preview'),
    tile = JSON.parse(readFileSync(join(dir, 'tileset.json')), 'utf8'),
    manifest = JSON.parse(readFileSync(join(dir, 'manifest.json'), 'utf8'))
const fail = []
const root = tile.root || {}
if (!Array.isArray(root.children) || root.children.length < 2) fail.push('root has fewer than two spatial children')
if (!root.content?.uri) fail.push('root must provide a valid GLB anchor for runtime traversal')
else {
    const anchor = readFileSync(join(dir, root.content.uri))
    if (anchor.toString('ascii', 0, 4) !== 'glTF' || anchor.readUInt32LE(4) !== 2 ||
        anchor.readUInt32LE(8) !== anchor.length || anchor.toString('ascii', 16, 20) !== 'JSON') {
        fail.push('root anchor GLB has invalid header')
    } else {
        try {
            JSON.parse(anchor.toString('utf8', 20, 20 + anchor.readUInt32LE(12)))
        } catch {
            fail.push('root anchor GLB has invalid JSON chunk')
        }
    }
}
const cellUris = []
for (const cell of root.children || []) {
    if (cell.refine !== 'REPLACE') fail.push('cell lacks REPLACE refinement')
    if (!cell.content?.uri) fail.push('cell lacks LOD1 content')
    else cellUris.push(cell.content.uri)
    if (cell.geometricError <= 0) fail.push('LOD1 cell geometricError must be positive')
    if (!Array.isArray(cell.children) || cell.children.length < 1) {
        fail.push('cell lacks LOD0 children')
        continue
    }
    for (const leaf of cell.children) {
        if (leaf.geometricError !== 0) fail.push('LOD0 leaf geometricError must be zero')
        if (!leaf.content?.uri) fail.push('LOD0 leaf lacks content')
        else cellUris.push(leaf.content.uri)
    }
}
for (const uri of cellUris) {
    if (!statSync(join(dir, uri), { throwIfNoEntry: false })) fail.push(`missing content ${uri}`)
}
const totals = manifest.totals || {}
if (!(totals.lod1?.bytes < totals.lod0?.bytes)) fail.push('LOD1 bytes are not below LOD0')
if (!(totals.lod1?.triangles < totals.lod0?.triangles)) fail.push('LOD1 triangles are not below LOD0')
if (manifest.count <= 0 || manifest.cellCount < 2) fail.push('manifest is empty')
if (fail.length) throw new Error(fail.join('\n'))
console.log(
    JSON.stringify({
        passed: true,
        scope: manifest.scope,
        cells: manifest.cellCount,
        count: manifest.count,
        low: totals.lod1,
        high: totals.lod0,
    })
)