export interface WorkbenchLayoutOptions {
  width: number
  contextOpen: boolean
  leftCollapsed: boolean
  rightCollapsed: boolean
  leftWidth: number
  rightWidth: number
  previewWidth: number
  rightTab: 'work' | 'files'
  filesView: 'list' | 'preview'
  previewOpen: boolean
  previewExpanded: boolean
}

export type WorkbenchPane = 'context' | 'conversation' | 'work' | 'files'
const COMPACT_WORKBENCH_WIDTH = 1024

function boundedWidth(value: number, fallback: number, min: number, max: number) {
  return Math.min(max, Math.max(min, Number.isFinite(value) ? value : fallback))
}

// Only the rendered widths are bounded. Saved desktop preferences stay in the store.
export function selectWorkbenchLayout(options: WorkbenchLayoutOptions) {
  const width = Number.isFinite(options.width) ? Math.max(0, options.width) : 1440
  const available = Math.max(0, width - 8)
  const compact = width < COMPACT_WORKBENCH_WIDTH
  const filesWide = options.rightTab === 'files' && options.filesView === 'preview' && options.previewOpen
  const previewExpanded = filesWide && options.previewExpanded && !options.rightCollapsed
  if (compact) {
    const pane: WorkbenchPane = options.contextOpen ? 'context' : options.rightCollapsed ? 'conversation' : options.rightTab
    return {
      compact, pane, showContext: pane === 'context', showConversation: pane === 'conversation',
      showRight: pane === 'work' || pane === 'files', contextCollapsed: false, previewExpanded,
      leftWidth: pane === 'context' ? available : 0,
      rightWidth: pane === 'work' || pane === 'files' ? available : 0,
      leftDivider: false, rightDivider: false,
    }
  }

  const showRight = !options.rightCollapsed
  const leftDivider = !options.leftCollapsed
  const rightDivider = showRight && !previewExpanded
  const panelCount = 1 + Number(!previewExpanded) + Number(showRight)
  const gutters = (panelCount - 1) * 4 + (Number(leftDivider) + Number(rightDivider)) * 8
  const leftMin = options.leftCollapsed ? 52 : 220
  const rightMin = showRight ? filesWide ? 420 : 280 : 0
  let leftWidth = options.leftCollapsed ? 52 : boundedWidth(options.leftWidth, 260, leftMin, 420)
  let rightWidth = showRight
    ? filesWide ? boundedWidth(options.previewWidth, 700, rightMin, 1100) : boundedWidth(options.rightWidth, 360, rightMin, 560)
    : 0
  if (previewExpanded) rightWidth = available - gutters - leftWidth
  else {
    const conversationMin = filesWide && showRight ? 320 : 360
    const budget = available - gutters - conversationMin
    if (leftWidth + rightWidth > budget) {
      const extraLeft = leftWidth - leftMin
      const extraRight = rightWidth - rightMin
      const ratio = Math.max(0, budget - leftMin - rightMin) / (extraLeft + extraRight || 1)
      leftWidth = leftMin + Math.floor(extraLeft * ratio)
      rightWidth = rightMin + Math.floor(extraRight * ratio)
    }
  }
  const pane: WorkbenchPane = previewExpanded ? 'files' : 'conversation'
  return {
    compact, pane,
    showContext: true, showConversation: !previewExpanded, showRight, contextCollapsed: options.leftCollapsed,
    previewExpanded, leftWidth, rightWidth, leftDivider, rightDivider,
  }
}