import { NavLink, useLocation } from 'react-router-dom'
import { useEffect, useMemo, useState } from 'react'
import { listInitiativeProjects } from '../api/projects.js'
import { listInitiativeActions } from '../api/initiatives.js'
import { listInitiativeBacklog } from '../api/backlog.js'
import { useProgramScope } from '../context/ProgramScopeContext.jsx'
import { buildProjectsByParent } from '../utils/projectTree.js'
import { projectPath } from '../utils/routes.js'
import {
  PLAN_OUTLINE_NODES,
  resolvePlanOutlineActiveKey,
  resolvePlanOutlineProjectId,
} from '../plan/planOutlineNodes.js'

function PlanOutlineProjectTree({ projects, parentId, activeProjectId, depth = 0 }) {
  const byParent = useMemo(() => buildProjectsByParent(projects), [projects])
  const nodes = byParent.get(parentId || '') || []

  if (nodes.length === 0) {
    return null
  }

  return (
    <ul className="analysis-split__nav-sublist">
      {nodes.map((project) => (
        <li key={project.id}>
          <NavLink
            to={projectPath(project.id)}
            className={({ isActive }) =>
              'analysis-split__nav-link analysis-split__nav-link--nested' +
              (isActive || activeProjectId === project.id
                ? ' analysis-split__nav-link--active'
                : '')
            }
          >
            {project.title}
          </NavLink>
          <PlanOutlineProjectTree
            projects={projects}
            parentId={project.id}
            activeProjectId={activeProjectId}
            depth={depth + 1}
          />
        </li>
      ))}
    </ul>
  )
}

export function PlanOutlineNav() {
  const location = useLocation()
  const { initiativeId, initiativeTitle, hrefWithScope } = useProgramScope()
  const activeKey = resolvePlanOutlineActiveKey(location.pathname)
  const activeProjectId = resolvePlanOutlineProjectId(location.pathname)
  const [counts, setCounts] = useState({ inbox: null, work: null })
  const [projects, setProjects] = useState([])
  const [structureOpen, setStructureOpen] = useState(
    activeKey === 'structure' || Boolean(activeProjectId),
  )

  useEffect(() => {
    setStructureOpen(activeKey === 'structure' || Boolean(activeProjectId))
  }, [activeKey, activeProjectId])

  useEffect(() => {
    if (!initiativeId) {
      setProjects([])
      return undefined
    }
    let cancelled = false
    listInitiativeProjects(initiativeId)
      .then((items) => {
        if (!cancelled) setProjects(Array.isArray(items) ? items : [])
      })
      .catch(() => {
        if (!cancelled) setProjects([])
      })
    return () => {
      cancelled = true
    }
  }, [initiativeId])

  useEffect(() => {
    if (!initiativeId) {
      setCounts({ inbox: null, work: null })
      return undefined
    }
    let cancelled = false
    Promise.all([
      listInitiativeBacklog(initiativeId).catch(() => []),
      listInitiativeActions(initiativeId).catch(() => []),
    ]).then(([backlog, actions]) => {
      if (cancelled) return
      setCounts({
        inbox: backlog.filter((item) => item.status !== 'converted').length,
        work: actions.filter(
          (action) => action.status !== 'done' && action.status !== 'discarded',
        ).length,
      })
    })
    return () => {
      cancelled = true
    }
  }, [initiativeId, location.pathname])

  function nodeLabel(node) {
    if (node.key === 'inbox' && counts.inbox != null) {
      return `${node.label} (${counts.inbox})`
    }
    if (node.key === 'work' && counts.work != null) {
      return `${node.label} (${counts.work})`
    }
    if (node.key === 'structure' && projects.length > 0) {
      return `${node.label} (${projects.length})`
    }
    return node.label
  }

  return (
    <nav className="analysis-split__nav" aria-label="Plan-Navigation">
      <div className="analysis-split__nav-header">
        <span className="analysis-split__nav-eyebrow">Planen</span>
        {initiativeId ? (
          <p className="analysis-split__nav-scope" title={initiativeTitle || initiativeId}>
            {initiativeTitle || 'Vorhaben'}
          </p>
        ) : (
          <p className="analysis-split__nav-scope analysis-split__nav-scope--muted">
            Portfolio — Vorhaben wählen
          </p>
        )}
      </div>

      <ul className="analysis-split__nav-list">
        {PLAN_OUTLINE_NODES.map((node) => {
          const needsInitiative = node.requiresInitiative && !initiativeId
          const isDisabled = node.disabled || needsInitiative
          const isStructure = node.key === 'structure'
          const hasProjectTree = isStructure && projects.length > 0 && initiativeId

          if (isDisabled) {
            return (
              <li key={node.key}>
                <span
                  className={
                    'analysis-split__nav-link analysis-split__nav-link--disabled' +
                    (activeKey === node.key ? ' analysis-split__nav-link--active' : '')
                  }
                  aria-disabled="true"
                  title={needsInitiative ? 'Vorhaben im Scope wählen' : node.hint}
                >
                  {nodeLabel(node)}
                </span>
              </li>
            )
          }

          return (
            <li key={node.key}>
              <div className="analysis-split__nav-row">
                {hasProjectTree && (
                  <button
                    type="button"
                    className="analysis-split__nav-toggle"
                    aria-expanded={structureOpen}
                    aria-label={structureOpen ? 'Struktur einklappen' : 'Struktur ausklappen'}
                    onClick={() => setStructureOpen((open) => !open)}
                  >
                    {structureOpen ? '▾' : '▸'}
                  </button>
                )}
                <NavLink
                  to={hrefWithScope(node.to)}
                  end
                  className={({ isActive }) =>
                    'analysis-split__nav-link' +
                    (isActive || (isStructure && activeProjectId)
                      ? ' analysis-split__nav-link--active'
                      : '')
                  }
                >
                  {nodeLabel(node)}
                </NavLink>
              </div>
              {hasProjectTree && structureOpen && (
                <PlanOutlineProjectTree
                  projects={projects}
                  parentId=""
                  activeProjectId={activeProjectId}
                />
              )}
            </li>
          )
        })}
      </ul>
    </nav>
  )
}