'use server'

import { revalidatePath } from 'next/cache'
import { cookies } from 'next/headers'
import { getIronSession } from 'iron-session'
import { z } from 'zod'
import { prisma } from '@/lib/prisma'
import { SessionData, sessionOptions } from '@/lib/session'
import { productAccessFilter } from '@/lib/product-access'
import { requireProductWriter } from '@/lib/auth'
import { taskSchema as sharedTaskSchema, type TaskInput } from '@/lib/schemas/task'
import { updateTaskStatusWithStoryPromotion } from '@/lib/tasks-status-update'
import { normalizeCode } from '@/lib/code'
import { createWithCodeRetry, generateNextTaskCode, isCodeUniqueConflict } from '@/lib/code-server'
import { enforceUserRateLimit } from '@/lib/rate-limit'

async function getSession() {
  return getIronSession<SessionData>(await cookies(), sessionOptions)
}

// Return types for TaskDialog actions
export type SaveTaskResult =
  | { ok: true; task: { id: string; title: string; status: string } }
  | { ok: false; code: 422; error: 'validation'; fieldErrors: Record<string, string[]> }
  | { ok: false; code: 403; error: 'demo_readonly' | 'forbidden' }
  | { ok: false; code: 429; error: 'rate_limited' }
  | { ok: false; code: 500; error: 'server_error' }

export type DeleteTaskResult =
  | { ok: true }
  | { ok: false; code: 403; error: 'demo_readonly' | 'forbidden' }
  | { ok: false; code: 500; error: 'server_error' }

// Unified create/edit action used by TaskDialog.
// context.taskId present → edit; context.storyId present → create.
export async function saveTask(
  input: TaskInput,
  context: { taskId?: string; storyId?: string; productId: string },
): Promise<SaveTaskResult> {
  const session = await getSession()
  if (!session.userId) return { ok: false, code: 403, error: 'forbidden' }
  if (session.isDemo) return { ok: false, code: 403, error: 'demo_readonly' }

  // Rate-limit alleen op create-path; edits zijn laag-volume.
  if (!context.taskId) {
    const limited = enforceUserRateLimit('create-task', session.userId)
    if (limited) return { ok: false, code: 429, error: 'rate_limited' }
  }

  const parsed = sharedTaskSchema.safeParse(input)
  if (!parsed.success) {
    return {
      ok: false,
      code: 422,
      error: 'validation',
      fieldErrors: parsed.error.flatten().fieldErrors as Record<string, string[]>,
    }
  }

  const { title, description, implementation_plan, priority, status, code: rawCode } = parsed.data
  const inputCode = normalizeCode(rawCode ?? null)
  const scope = productAccessFilter(session.userId)

  try {
    if (context.taskId) {
      const existing = await prisma.task.findFirst({
        where: { id: context.taskId, story: { product: scope } },
        select: { id: true, status: true },
      })
      if (!existing) return { ok: false, code: 403, error: 'forbidden' }

      const taskId = context.taskId
      const statusChanged = status !== undefined && status !== existing.status

      const task = await prisma.$transaction(async (tx) => {
        const updated = await tx.task.update({
          where: { id: taskId },
          data: {
            title,
            description: description ?? null,
            implementation_plan: implementation_plan ?? null,
            priority,
          },
          select: { id: true, title: true, status: true },
        })

        if (statusChanged) {
          const result = await updateTaskStatusWithStoryPromotion(taskId, status, tx)
          return { id: result.task.id, title: result.task.title, status: result.task.status }
        }
        return updated
      })

      revalidatePath(`/products/${context.productId}/sprint`)
      revalidatePath(`/products/${context.productId}`)
      return { ok: true, task: { ...task, status: task.status.toString() } }
    }

    if (!context.storyId) {
      return { ok: false, code: 422, error: 'validation', fieldErrors: { storyId: ['Verplicht'] } }
    }

    const story = await prisma.story.findFirst({
      where: { id: context.storyId, product: scope },
      select: { sprint_id: true, product_id: true },
    })
    if (!story) return { ok: false, code: 403, error: 'forbidden' }

    const last = await prisma.task.findFirst({
      where: { story_id: context.storyId },
      orderBy: { sort_order: 'desc' },
      select: { sort_order: true },
    })

    const productId = story.product_id
    const sprintId = story.sprint_id ?? null
    const sortOrder = (last?.sort_order ?? 0) + 1.0
    const storyId = context.storyId

    const task = await createWithCodeRetry(
      () => (inputCode ? Promise.resolve(inputCode) : generateNextTaskCode(productId)),
      (code) =>
        prisma.task.create({
          data: {
            story_id: storyId,
            product_id: productId,
            sprint_id: sprintId,
            code,
            title,
            description: description ?? null,
            implementation_plan: implementation_plan ?? null,
            priority,
            sort_order: sortOrder,
            status: 'TO_DO',
          },
          select: { id: true, title: true, status: true },
        }),
    )

    revalidatePath(`/products/${context.productId}/sprint`)
    revalidatePath(`/products/${context.productId}`)
    return { ok: true, task: { ...task, status: task.status.toString() } }
  } catch (e) {
    if (inputCode && isCodeUniqueConflict(e)) {
      return {
        ok: false,
        code: 422,
        error: 'validation',
        fieldErrors: { code: ['Code bestaat al binnen dit product'] },
      }
    }
    return { ok: false, code: 500, error: 'server_error' }
  }
}

// Delete action used by TaskDialog (context-aware revalidation).
export async function deleteTask(
  taskId: string,
  context: { productId: string },
): Promise<DeleteTaskResult> {
  const session = await getSession()
  if (!session.userId) return { ok: false, code: 403, error: 'forbidden' }
  if (session.isDemo) return { ok: false, code: 403, error: 'demo_readonly' }

  try {
    const task = await prisma.task.findFirst({
      where: { id: taskId, story: { product: productAccessFilter(session.userId) } },
    })
    if (!task) return { ok: false, code: 403, error: 'forbidden' }

    await prisma.task.delete({ where: { id: taskId } })

    revalidatePath(`/products/${context.productId}/sprint`)
    revalidatePath(`/products/${context.productId}`)
    return { ok: true }
  } catch {
    return { ok: false, code: 500, error: 'server_error' }
  }
}

const taskSchema = z.object({
  title: z.string().min(1, 'Titel is verplicht').max(200),
  description: z.string().max(1000).optional(),
  priority: z.coerce.number().int().min(1).max(4),
})

export async function createTaskAction(_prevState: unknown, formData: FormData) {
  const session = await getSession()
  if (!session.userId) return { error: 'Niet ingelogd' }
  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }

  const limited = enforceUserRateLimit('create-task', session.userId)
  if (limited) return limited

  const storyId = formData.get('storyId') as string
  const sprintId = formData.get('sprintId') as string

  const parsed = taskSchema.safeParse({
    title: formData.get('title'),
    description: formData.get('description') || undefined,
    priority: formData.get('priority') ?? 2,
  })
  if (!parsed.success) return { error: parsed.error.flatten().fieldErrors }

  const story = await prisma.story.findFirst({
    where: { id: storyId, product: productAccessFilter(session.userId) },
  })
  if (!story) return { error: 'Story niet gevonden' }

  const last = await prisma.task.findFirst({
    where: { story_id: storyId },
    orderBy: { sort_order: 'desc' },
  })

  const productId = story.product_id
  const task = await createWithCodeRetry(
    () => generateNextTaskCode(productId),
    (code) =>
      prisma.task.create({
        data: {
          story_id: storyId,
          product_id: productId,
          sprint_id: sprintId || null,
          code,
          title: parsed.data.title,
          description: parsed.data.description ?? null,
          priority: parsed.data.priority,
          sort_order: (last?.sort_order ?? 0) + 1.0,
          status: 'TO_DO',
        },
      }),
  )

  revalidatePath(`/products/${story.product_id}/sprint/planning`)
  return { success: true, task }
}

export async function updateTaskAction(_prevState: unknown, formData: FormData) {
  const session = await getSession()
  if (!session.userId) return { error: 'Niet ingelogd' }
  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }

  const id = formData.get('id') as string
  const parsed = taskSchema.safeParse({
    title: formData.get('title'),
    description: formData.get('description') || undefined,
    priority: formData.get('priority'),
  })
  if (!parsed.success) return { error: parsed.error.flatten().fieldErrors }

  const task = await prisma.task.findFirst({
    where: { id, story: { product: productAccessFilter(session.userId) } },
    include: { story: true },
  })
  if (!task) return { error: 'Taak niet gevonden' }

  await prisma.task.update({
    where: { id },
    data: { title: parsed.data.title, description: parsed.data.description ?? null, priority: parsed.data.priority },
  })

  revalidatePath(`/products/${task.story.product_id}/sprint/planning`)
  return { success: true }
}

export async function updateTaskStatusAction(id: string, status: 'TO_DO' | 'IN_PROGRESS' | 'DONE') {
  const session = await getSession()
  if (!session.userId) return { error: 'Niet ingelogd' }
  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }

  const task = await prisma.task.findFirst({
    where: { id, story: { product: productAccessFilter(session.userId) } },
    include: { story: true },
  })
  if (!task) return { error: 'Taak niet gevonden' }

  await updateTaskStatusWithStoryPromotion(id, status)

  // /solo bewust niet revalideren: dat zou de page soft-navigaten en de
  // open SSE-stream sluiten. De Solo Paneel-flow leunt op optimistic
  // store-updates + realtime echo (M8). Sprint/planning heeft geen
  // realtime en moet wèl revalidaten.
  revalidatePath(`/products/${task.story.product_id}/sprint/planning`)
  return { success: true }
}

export async function deleteTaskAction(id: string) {
  const session = await getSession()
  if (!session.userId) return { error: 'Niet ingelogd' }
  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }

  const task = await prisma.task.findFirst({
    where: { id, story: { product: productAccessFilter(session.userId) } },
    include: { story: true },
  })
  if (!task) return { error: 'Taak niet gevonden' }

  await prisma.task.delete({ where: { id } })

  revalidatePath(`/products/${task.story.product_id}/sprint/planning`)
  return { success: true }
}

const updateTaskPlanSchema = z.object({
  taskId: z.string().min(1),
  productId: z.string().min(1),
  implementationPlan: z.string().max(10000),
})

export async function updateTaskPlanAction(taskId: string, productId: string, implementationPlan: string) {
  try {
    await requireProductWriter(productId)
  } catch (e) {
    return { error: e instanceof Error ? e.message : 'Niet geautoriseerd' }
  }

  const parsed = updateTaskPlanSchema.safeParse({ taskId, productId, implementationPlan })
  if (!parsed.success) return { error: 'Ongeldige invoer' }

  const task = await prisma.task.findFirst({
    where: { id: taskId, story: { product_id: productId } },
    include: { story: true },
  })
  if (!task) return { error: 'Taak niet gevonden' }

  await prisma.task.update({
    where: { id: taskId },
    data: { implementation_plan: implementationPlan || null },
  })

  // /solo bewust niet revalideren — zie updateTaskStatusAction.
  revalidatePath(`/products/${productId}/sprint/planning`)
  return { success: true }
}

export async function reorderTasksAction(storyId: string, orderedIds: string[]) {
  const session = await getSession()
  if (!session.userId) return { error: 'Niet ingelogd' }
  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }

  const story = await prisma.story.findFirst({
    where: { id: storyId, product: productAccessFilter(session.userId) },
  })
  if (!story) return { error: 'Story niet gevonden' }

  await prisma.$transaction(
    orderedIds.map((id, i) =>
      prisma.task.update({ where: { id }, data: { sort_order: i + 1.0 } })
    )
  )

  revalidatePath(`/products/${story.product_id}/sprint/planning`)
  return { success: true }
}