/**
 * Servicio genérico de grafos en capas (columnas).
 *
 * Provee un layout determinista por columnas (un tipo por columna) y un
 * adaptador al formato `elements` de cytoscape.js. No conoce el dominio
 * (provenance, organigrama, etc.), solo el modelo de grafo:
 *   node: { id, kind, label, image?, entity? }
 *   edge: { from, to }  (ids de los nodos)
 */

const DEFAULTS = {
  columnWidth: 220,
  rowHeight: 64,
  padding: 24,
}

function groupByColumn (nodes, columnOf) {
  const columns = {}
  for (const node of nodes) {
    const column = columnOf(node) ?? 0
    if (!columns[column]) columns[column] = []
    columns[column].push(node)
  }
  return columns
}

export function computeColumnLayout (nodes, edges, options = {}) {
  const { columnOf, columnWidth = DEFAULTS.columnWidth, rowHeight = DEFAULTS.rowHeight, padding = DEFAULTS.padding } = options
  const columns = groupByColumn(nodes, columnOf)
  const columnKeys = Object.keys(columns).map(Number)
  const maxColumn = columnKeys.length > 0 ? Math.max(...columnKeys) : 0
  const maxRows = columnKeys.length > 0 ? Math.max(...columnKeys.map(c => columns[c].length)) : 0

  const positionedNodes = nodes.map(node => {
    const column = columnOf(node) ?? 0
    const index = columns[column].indexOf(node)
    return {
      ...node,
      x: padding + column * columnWidth + columnWidth / 2,
      y: padding + index * rowHeight + rowHeight / 2,
    }
  })

  return {
    nodes: positionedNodes,
    edges,
    width: padding * 2 + (maxColumn + 1) * columnWidth,
    height: padding * 2 + maxRows * rowHeight,
  }
}

export function toCytoscapeElements ({ nodes, edges }) {
  return [
    ...nodes.map(node => {
      const classes = node.image ? [node.kind, 'has-image'] : [node.kind]
      return {
        data: {
          id: node.id,
          kind: node.kind,
          label: node.label,
          image: node.image || null,
          entity: node.entity || null,
        },
        classes,
        position: { x: node.x, y: node.y },
      }
    }),
    ...edges.map(edge => ({
      data: {
        id: `edge:${edge.from}:${edge.to}`,
        source: edge.from,
        target: edge.to,
      },
    })),
  ]
}