import { useState, useEffect } from 'react'
import { useParams, useNavigate } from 'react-router-dom'
import api from '@/services/api'
import type { Project, ProjectMember, Milestone } from '@/types'
import dayjs from 'dayjs'

export default function ProjectDetailPage() {
  const { id } = useParams()
  const navigate = useNavigate()
  const [project, setProject] = useState<Project | null>(null)
  const [members, setMembers] = useState<ProjectMember[]>([])
  const [milestones, setMilestones] = useState<Milestone[]>([])
  const [allProjects, setAllProjects] = useState<Project[]>([])
  const [showAddMember, setShowAddMember] = useState(false)
  const [showAddMilestone, setShowAddMilestone] = useState(false)
  const [newMemberUserId, setNewMemberUserId] = useState(1)
  const [newMemberRole, setNewMemberRole] = useState('developer')
  const [newMilestoneTitle, setNewMilestoneTitle] = useState('')
  const [users, setUsers] = useState<any[]>([])
  const [roles, setRoles] = useState<any[]>([])
  const [editing, setEditing] = useState(false)
  const [editForm, setEditForm] = useState({ owner: '', repo: '', description: '', sub_projects: [] as string[], related_projects: [] as string[] })

  useEffect(() => {
    api.get<Project>(`/projects/${id}`).then(({ data }) => {
      setProject(data)
      setEditForm({
        owner: data.owner_name || data.owner || '',
        repo: data.repo || '',
        description: data.description || '',
        sub_projects: data.sub_projects || [],
        related_projects: data.related_projects || [],
      })
    })
    api.get<ProjectMember[]>(`/projects/${id}/members`).then(({ data }) => setMembers(data))
    api.get<Milestone[]>(`/milestones?project_id=${id}`).then(({ data }) => setMilestones(data))
    api.get<Project[]>('/projects').then(({ data }) => setAllProjects(data))
    api.get('/users').then(r => setUsers(r.data)).catch(() => {})
    api.get('/roles').then(r => setRoles(r.data)).catch(() => {})
    api.get('/users').then(r => setUsers(r.data)).catch(() => {})
  }, [id])

  const handleMulti = (e: React.ChangeEvent<HTMLSelectElement>, field: 'sub_projects' | 'related_projects') => {
    const values = Array.from(e.target.selectedOptions).map((o) => o.value)
    setEditForm({ ...editForm, [field]: values })
  }

  const updateProject = async (e: React.FormEvent) => {
    e.preventDefault()
    const { data } = await api.patch<Project>(`/projects/${id}`, editForm)
    setProject(data)
    setEditing(false)
  }

  const addMember = async () => {
    if (!newMemberUserId) return
    await api.post(`/projects/${id}/members`, { user_id: newMemberUserId, role: newMemberRole })
    setShowAddMember(false)
    api.get<ProjectMember[]>(`/projects/${id}/members`).then(({ data }) => setMembers(data))
  }

  const removeMember = async (userId: number, role: string) => {
    // Prevent removing owner
    if (role === 'admin') {
      alert('Cannot remove project owner (admin)')
      return
    }
    if (!confirm('Remove this member?')) return
    await api.delete(`/projects/${id}/members/${userId}`)
    api.get<ProjectMember[]>(`/projects/${id}/members`).then(({ data }) => setMembers(data))
  }

  const addMilestone = async () => {
    if (!newMilestoneTitle.trim()) return
    await api.post(`/projects/${id}/milestones`, { title: newMilestoneTitle, status: 'open' })
    setShowAddMilestone(false)
    setNewMilestoneTitle('')
    api.get<Milestone[]>(`/projects/${id}/milestones`).then(({ data }) => setMilestones(data)).catch(() => {})
  }

  const deleteProject = async () => {
    const confirmName = prompt(`Type the project name "${project?.name}" to confirm deletion:`)
    if (confirmName !== project?.name) {
      alert('Project name does not match. Deletion cancelled.')
      return
    }
    await api.delete(`/projects/${id}`)
    navigate('/projects')
  }

  if (!project) return <div className="loading">Loading...</div>

  const selectableProjects = allProjects.filter((p) => p.id !== project.id && p.project_code)

  return (
    <div className="project-detail">
      <button className="btn-back" onClick={() => navigate('/projects')}>← Back to projects</button>

      <div className="task-header">
        {editing ? (
          <form className="inline-form" onSubmit={updateProject}>
            <div style={{ fontWeight: 600 }}>{project.name}</div>
            {project.project_code && <span className="badge">{project.project_code}</span>}
            <select value={editForm.owner} onChange={(e) => setEditForm({ ...editForm, owner: e.target.value })}>
              {users.map((u: any) => <option key={u.id} value={u.username}>{u.username} ({u.full_name})</option>)}
            </select>
            <input value={editForm.description} onChange={(e) => setEditForm({ ...editForm, description: e.target.value })} placeholder="Description" />
            <input value={editForm.repo} onChange={(e) => setEditForm({ ...editForm, repo: e.target.value })} placeholder="Repository URL" />
            <label>Sub-projects
              <select multiple value={editForm.sub_projects} onChange={(e) => handleMulti(e, 'sub_projects')}>
                {selectableProjects.map((p) => (
                  <option key={p.id} value={p.project_code || ''}>{p.project_code || p.name}</option>
                ))}
              </select>
            </label>
            <label>Related projects
              <select multiple value={editForm.related_projects} onChange={(e) => handleMulti(e, 'related_projects')}>
                {selectableProjects.map((p) => (
                  <option key={p.id} value={p.project_code || ''}>{p.project_code || p.name}</option>
                ))}
              </select>
            </label>
            <button type="submit" className="btn-primary">Save</button>
            <button type="button" className="btn-back" onClick={() => setEditing(false)}>Cancel</button>
          </form>
        ) : (
          <>
            <h2>📁 {project.name} {project.project_code && <span className="badge">{project.project_code}</span>}</h2>
            <p style={{ color: 'var(--text-dim)', marginTop: 4 }}>{project.description || 'No description'}</p>
            {project.repo && <p style={{ color: 'var(--text-dim)', marginTop: 4 }}>📦 {project.repo}</p>}
            <div className="text-dim">Owner: {project.owner_name || project.owner || "Unknown"}</div>
            <button className="btn-transition" style={{ marginTop: 8 }} onClick={() => setEditing(true)}>Edit</button>
            <button className="btn-danger" style={{ marginLeft: 8 }} onClick={deleteProject}>Delete</button>
          </>
        )}
      </div>

      <div className="section">
        <h3>Members ({members.length}) <button className="btn-sm" onClick={() => setShowAddMember(true)}>+ Add</button></h3>
        {members.length > 0 ? (
          <div className="member-list">
            {members.map((m) => (
              <span key={m.id} className="badge" style={{marginRight: 8}}>
                {`User #${m.user_id} (${m.role})`}
                <button onClick={(e) => { e.stopPropagation(); removeMember(m.user_id, m.role) }} style={{marginLeft: 8, background: 'none', border: 'none', color: 'red', cursor: 'pointer'}}>×</button>
              </span>
            ))}
          </div>
        ) : (
          <p className="empty">No members</p>
        )}
      </div>

      <div className="section">
        <h3>Milestones ({milestones.length}) <button className="btn-sm" onClick={() => setShowAddMilestone(true)}>+ New</button></h3>
        {milestones.map((ms) => (
          <div key={ms.id} className="milestone-item" onClick={() => navigate(`/milestones/${ms.id}`)}>
            <span className={`badge status-${ms.status === 'open' ? 'open' : ms.status === 'closed' ? 'closed' : 'in_progress'}`}>{ms.status}</span>
            <span className="milestone-title">{ms.title}</span>
            {ms.due_date && <span className="text-dim"> · Due {dayjs(ms.due_date).format('YYYY-MM-DD')}</span>}
          </div>
        ))}
        {milestones.length === 0 && <p className="empty">No milestones</p>}
      </div>

      {showAddMember && (
        <div className="modal-overlay" onClick={() => setShowAddMember(false)}>
          <div className="modal" onClick={e => e.stopPropagation()}>
            <h3>Add Member</h3>
            <select value={newMemberUserId} onChange={e => setNewMemberUserId(Number(e.target.value))}>
              {users.map(u => <option key={u.id} value={u.id}>{u.username} ({u.full_name})</option>)}
            </select>
            <select value={newMemberRole} onChange={e => setNewMemberRole(e.target.value)}>
              {roles.map(r => <option key={r.id} value={r.name}>{r.name}</option>)}
            </select>
            <div style={{marginTop: 10}}>
              <button className="btn-primary" onClick={addMember}>Add</button>
              <button className="btn-back" onClick={() => setShowAddMember(false)}>Cancel</button>
            </div>
          </div>
        </div>
      )}

      {showAddMilestone && (
        <div className="modal-overlay" onClick={() => setShowAddMilestone(false)}>
          <div className="modal" onClick={e => e.stopPropagation()}>
            <h3>New Milestone</h3>
            <input value={newMilestoneTitle} onChange={e => setNewMilestoneTitle(e.target.value)} placeholder="Milestone title" />
            <div style={{marginTop: 10}}>
              <button className="btn-primary" onClick={addMilestone}>Create</button>
              <button className="btn-back" onClick={() => setShowAddMilestone(false)}>Cancel</button>
            </div>
          </div>
        </div>
      )}
    </div>
  )
}