import { useState } from 'react'
import type { ReactElement } from 'react'
import type { BatchStage, BoardTab } from '../types'
import type { Project } from '../project'
import { PROJECT_LABEL } from '../project'
import { IconSpend, IconPage, IconLoop, IconIdCard, IconPatients } from './icons'

/**
 * The app-wide section rail, at a fixed 236px.
 *
 * It used to collapse to a 56px icon strip and expand to an overlay on hover.
 * That is gone with the reskin: the rail is now always labelled, which is what
 * the approved mockup shows and what removes the "hover to find out what these
 * icons are" step from every navigation.
 *
 * Two projects, one rail: ECW's boards (templates 1-6) and Tebra's (template 7
 * / Gulf Coast), each under its own group header. See project.ts for how a
 * batch or run is assigned to one or the other.
 *
 * Selection and drag-and-drop-to-move-stage behaviour are unchanged — only the
 * shape of the control moved.
 */
export function Sidebar({
  tab,
  onTab,
  counts,
  onDropBatch,
  onDropRun,
  isAdmin,
  projects,
}: {
  tab: BoardTab
  onTab: (t: BoardTab) => void
  /** Per project, per stage — each section shows its own queue depth. */
  counts: Record<Project, Record<BatchStage, number>>
  /** A batch card dragged onto a section moves to that stage. */
  onDropBatch: (batchId: string, stage: BatchStage) => void
  /** A single document dragged onto Automation is gathered into its own batch. */
  onDropRun?: (jobId: string) => void
  /** Gates each section's ROI item, and the single account-level People
   *  item below them all — both are admin-and-above. */
  isAdmin: boolean
  /** Which sections render at all. A scoped admin sees one; everyone else sees
   *  both. Independent of `isAdmin`: an operator sees both sections' boards
   *  with ROI/People hidden inside each, while a scoped admin has a whole
   *  section absent regardless of role. */
  projects: Project[]
}) {
  return (
    <nav
      aria-label="Sections"
      className="sb-rail z-10 w-[236px] shrink-0 overflow-y-auto"
    >
      {projects.includes('ecw') && (
        <>
          <SectionHead project="ecw" first={projects[0] === 'ecw'} />
          {/* First, and deliberately not a drop target: ROI is a report over the
              whole pipeline, not a place a batch can be put. Passing no
              `dropStage` is what makes dropping onto it impossible, rather than
              a handler that quietly does nothing. */}
          {isAdmin && (
            <Item
              tab="roi"
              icon={IconSpend}
              label="ROI Dashboard"
              hint="What the pipeline has cost, and what that bought"
              active={tab === 'roi'}
              onSelect={onTab}
            />
          )}
          <Item
            tab="extraction"
            dropStage="extraction"
            dropTab="extraction"
            icon={IconPage}
            label="Charge Extraction"
            hint="Drop PDFs, run the extractor, clear the flagged fields"
            active={tab === 'extraction'}
            n={counts.ecw.extraction}
            onSelect={onTab}
            onDropBatch={onDropBatch}
            onDropRun={onDropRun}
          />
          {/* Demography's own spend, apart from the charges ROI above (ticket
              05). Admin only, the same rule as the other ROI items. */}
          {isAdmin && (
            <Item
              tab="demography-roi"
              icon={IconSpend}
              label="Demography ROI"
              hint="What demography extraction has cost, and what that bought"
              active={tab === 'demography-roi'}
              onSelect={onTab}
            />
          )}
          <Item
            tab="demography"
            icon={IconIdCard}
            label="Demography Extraction"
            hint="OCR-only extraction for facesheets and admission records"
            active={tab === 'demography'}
            onSelect={onTab}
          />
          <Item
            tab="automation"
            dropStage="automation"
            dropTab="automation"
            icon={IconLoop}
            label="Charge Automation"
            hint="Batches that finished extraction and are ready to post"
            active={tab === 'automation'}
            n={counts.ecw.automation}
            onSelect={onTab}
            onDropBatch={onDropBatch}
            onDropRun={onDropRun}
          />
          {/* Not a drop target, same reasoning as Demography Extraction above:
              a demography run is not a batch, so BATCH_DRAG_TYPE's payload
              (a batch_id) has nowhere to go here. */}
          <Item
            tab="demography-automation"
            icon={IconIdCard}
            label="Demography Automation"
            hint="Demography runs that finished and are ready to post"
            active={tab === 'demography-automation'}
            onSelect={onTab}
          />
        </>
      )}

      {projects.includes('tebra') && (
        <>
          <SectionHead project="tebra" first={projects[0] === 'tebra'} />
          {isAdmin && (
            <Item
              tab="tebra-roi"
              icon={IconSpend}
              label="ROI Dashboard"
              hint="What the Gulf Coast pipeline has cost, and what that bought"
              active={tab === 'tebra-roi'}
              onSelect={onTab}
            />
          )}
          <Item
            tab="tebra-extraction"
            dropStage="extraction"
            dropTab="tebra-extraction"
            icon={IconPage}
            label="Gulf Coast Charge Extraction"
            hint="Gulf Coast tickets: extract and clear the flagged fields"
            active={tab === 'tebra-extraction'}
            n={counts.tebra.extraction}
            onSelect={onTab}
            onDropBatch={onDropBatch}
            onDropRun={onDropRun}
          />
          <Item
            tab="tebra-automation"
            dropStage="automation"
            dropTab="tebra-automation"
            icon={IconLoop}
            label="Gulf Coast Charge Automation"
            hint="Gulf Coast batches that finished extraction and are ready to post"
            active={tab === 'tebra-automation'}
            n={counts.tebra.automation}
            onSelect={onTab}
            onDropBatch={onDropBatch}
            onDropRun={onDropRun}
          />
        </>
      )}

      {/* One People entry for the whole app, below every project section
          rather than inside one — access is an account-level thing, not a
          board, and a copy under each project only ever asked "which of these
          two identical links did I mean". The screen itself is merged for
          anyone who can see both projects (see UsersPanel); a single-project
          admin lands on their own project's screen, which is why the tab id
          follows `projects` rather than being fixed — 'people' maps to ECW,
          and a Tebra-only admin must not be sent to a board they cannot see
          (App.tsx bounces them straight back off it).

          Not a drop target: this is settings. Admins need it to grant access;
          operators have nothing to do here and the endpoint would refuse them
          anyway. */}
      {isAdmin && (
        <>
          <hr className="sb-rail-divider" />
          <Item
            tab={projects.includes('ecw') ? 'people' : 'tebra-people'}
            icon={IconPatients}
            label="User Access"
            hint="Who can sign in, and what each of them may do"
            active={tab === 'people' || tab === 'tebra-people'}
            onSelect={onTab}
          />
        </>
      )}
    </nav>
  )
}

/** One project's name above its own nav list, with the bar glyph the mockup
 *  uses for a group header. The divider is skipped on the first section —
 *  there is nothing yet to divide it from. */
function SectionHead({ project, first }: { project: Project; first: boolean }) {
  return (
    <>
      {!first && <hr className="sb-rail-divider" />}
      <div className="sb-rail-group">
        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" aria-hidden="true">
          <path d="M5 20V11M12 20V5M19 20V14" />
        </svg>
        <span className="whitespace-pre-line">{PROJECT_LABEL[project]}</span>
      </div>
    </>
  )
}

export const BATCH_DRAG_TYPE = 'application/x-superbill-batch'
const RUN_DRAG_TYPE = 'application/x-superbill-run'

function Item({
  tab,
  dropStage,
  dropTab,
  icon: IconEl,
  label,
  hint,
  active,
  n,
  onSelect,
  onDropBatch,
  onDropRun,
}: {
  tab: BoardTab
  /** The stage a card dropped here should move to. Absent on sections that
   *  are a view rather than a place, which is what makes them reject a drop. */
  dropStage?: BatchStage
  /** The board to navigate to after a drop. Two projects can share a stage
   *  name (both have an "extraction" and an "automation"), so the stage alone
   *  no longer identifies which board a card landed on — this does. Defaults
   *  to `tab`, which was the drop target anyway on every item that has one. */
  dropTab?: BoardTab
  icon: (p: { size?: number; className?: string }) => ReactElement
  label: string
  hint: string
  active: boolean
  /** Omitted on sections that count nothing — a report has no queue depth. */
  n?: number
  onSelect: (t: BoardTab) => void
  onDropBatch?: (batchId: string, stage: BatchStage) => void
  onDropRun?: (jobId: string) => void
}) {
  const [over, setOver] = useState(false)

  return (
    <button
      type="button"
      onClick={() => onSelect(tab)}
      title={hint}
      aria-current={active ? 'page' : undefined}
      // A section is also a drop target, so a batch — or a single document —
      // can be thrown at "Automation" without first switching to it and
      // losing sight of the card being dragged.
      onDragOver={(e) => {
        if (!dropStage) return
        const t = e.dataTransfer.types
        if (t.includes(BATCH_DRAG_TYPE) || (onDropRun && t.includes(RUN_DRAG_TYPE))) {
          e.preventDefault()
          e.dataTransfer.dropEffect = 'move'
          setOver(true)
        }
      }}
      onDragLeave={() => setOver(false)}
      onDrop={(e) => {
        if (!dropStage) return
        setOver(false)
        const batchId = e.dataTransfer.getData(BATCH_DRAG_TYPE)
        const runId = e.dataTransfer.getData(RUN_DRAG_TYPE)
        if (!batchId && !runId) return
        e.preventDefault()
        if (batchId && onDropBatch) onDropBatch(batchId, dropStage)
        else if (runId && onDropRun) onDropRun(runId)
        // Navigate to the board that was dropped ON, not to the stage name —
        // see the `dropTab` prop doc above.
        onSelect(dropTab ?? tab)
      }}
      className={`sb-nav-item ${over ? 'bg-surface-2 text-ink-2' : ''}`}
    >
      <IconEl size={16} className="shrink-0" />
      <span className="truncate">{label}</span>
      {n !== undefined && (
        // Red only when the number is work somebody has to pick up. A badge
        // that is red at zero teaches people to stop reading it.
        <span className={`sb-count ${n > 0 ? 'sb-count-hot' : ''}`}>{n}</span>
      )}
    </button>
  )
}