screen_checklists_ui <- function(id) {
  ns <- NS(id)
  bslib::navset_card_tab(
    bslib::nav_panel("Ausführen",
      shiny::div(class = "p-2",
        shiny::uiOutput(ns("checklist_sel")),
        shiny::uiOutput(ns("run_items"))
      )
    ),
    bslib::nav_panel("Verwalten",
      shiny::div(class = "p-2",
        shiny::div(class = "d-flex gap-2 mb-3",
          shiny::textInput(ns("new_name"), NULL, placeholder = "Neue Checkliste..."),
          shiny::selectInput(ns("new_scope"), NULL,
            choices = c("Volk" = "colony", "Stand" = "apiary"), width = "120px"),
          shiny::actionButton(ns("add_list"), shiny::icon("plus"), class = "btn btn-primary")
        ),
        shiny::uiOutput(ns("manage_list"))
      )
    )
  )
}

screen_checklists_server <- function(id, db, nav) {
  moduleServer(id, function(input, output, session) {
    ns       <- session$ns
    reload   <- reactiveVal(0)
    sel_list <- reactiveVal(NULL)

    checklists <- reactive({ reload(); db_checklists_list(db) })

    output$checklist_sel <- renderUI({
      cls <- checklists()
      if (nrow(cls) == 0)
        return(shiny::p(class = "text-muted", "Noch keine Checklisten. Im Tab 'Verwalten' anlegen."))
      shiny::selectInput(ns("run_list"), "Checkliste",
        choices = c("Bitte wählen" = "", setNames(cls$id,
          paste0("[", cls$scope, "] ", cls$name)))
      )
    })

    output$run_items <- renderUI({
      req(input$run_list, input$run_list != "", nav$colony_id)
      lid      <- as.integer(input$run_list)
      scope_id <- nav$colony_id
      date     <- as.character(Sys.Date())
      items    <- db_checklist_items_list(db, lid)
      if (nrow(items) == 0) return(shiny::p(class = "text-muted", "Keine Einträge."))
      done  <- db_checklist_completions_list(db, lid, scope_id, date)

      shiny::div(class = "list-group",
        lapply(seq_len(nrow(items)), function(i) {
          item      <- items[i, ]
          completed <- item$id %in% done$item_id
          shiny::div(
            class = paste("list-group-item d-flex align-items-center gap-3 py-3",
              if (completed) "list-group-item-success" else ""),
            shiny::tags$input(
              class   = "form-check-input flex-shrink-0",
              type    = "checkbox",
              checked = if (completed) NA else NULL,
              style   = "width:1.3em;height:1.3em;cursor:pointer",
              onclick = sprintf(
                "Shiny.setInputValue('%s',{id:%d},  {priority:'event'})",
                ns("toggle"), item$id
              )
            ),
            shiny::span(item$text,
              style = if (completed) "text-decoration:line-through;opacity:.6" else "")
          )
        })
      )
    })

    observeEvent(input$toggle, {
      req(input$run_list, nav$colony_id)
      db_checklist_completions_toggle(db,
        checklist_id = as.integer(input$run_list),
        item_id      = as.integer(input$toggle$id),
        scope_id     = nav$colony_id,
        date         = as.character(Sys.Date())
      )
    })

    # ---- Manage tab ---------------------------------------------------------
    output$manage_list <- renderUI({
      cls <- checklists()
      if (nrow(cls) == 0) return(shiny::p(class = "text-muted", "Keine Checklisten."))
      lapply(seq_len(nrow(cls)), function(i) {
        row <- cls[i, ]
        shiny::div(class = "card mb-2",
          bslib::card_body(
            class = "py-2",
            shiny::div(class = "d-flex justify-content-between align-items-center",
              shiny::div(
                shiny::tags$strong(row$name),
                shiny::tags$small(class = "text-muted ms-2", paste0("[", row$scope, "]"))
              ),
              shiny::div(
                shiny::actionButton(ns(paste0("sel_", row$id)), "Einträge",
                  class = "btn btn-sm btn-outline-secondary me-1"),
                shiny::actionButton(ns(paste0("del_list_", row$id)), shiny::icon("trash"),
                  class = "btn btn-sm btn-outline-danger")
              )
            ),
            shiny::uiOutput(ns(paste0("items_", row$id)))
          )
        )
      })
    })

    observe({
      cls <- checklists()
      lapply(cls$id, function(lid) {
        local({
          llid <- lid
          observeEvent(input[[paste0("sel_", llid)]], sel_list(llid), ignoreInit = TRUE)
          observeEvent(input[[paste0("del_list_", llid)]], {
            db_checklists_delete(db, llid)
            if (identical(sel_list(), llid)) sel_list(NULL)
            reload(reload() + 1L)
          }, ignoreInit = TRUE)
        })
      })
    })

    observe({
      lid <- sel_list()
      req(lid)
      items <- db_checklist_items_list(db, lid)
      output[[paste0("items_", lid)]] <- renderUI({
        shiny::div(class = "mt-2",
          if (nrow(items) > 0)
            shiny::tags$ul(class = "list-unstyled mb-2",
              lapply(seq_len(nrow(items)), function(i) {
                it <- items[i, ]
                shiny::tags$li(class = "d-flex justify-content-between align-items-center small py-1 border-bottom",
                  it$text,
                  shiny::actionButton(ns(paste0("del_item_", it$id)), "×",
                    class = "btn btn-sm btn-link text-danger p-0",
                    onclick = "event.stopPropagation()"
                  )
                )
              })
            ),
          shiny::div(class = "d-flex gap-2",
            shiny::textInput(ns(paste0("item_txt_", lid)), NULL, placeholder = "Neuer Eintrag..."),
            shiny::actionButton(ns(paste0("add_item_", lid)), shiny::icon("plus"),
              class = "btn btn-outline-primary")
          )
        )
      })
      lapply(items$id, function(iid) {
        local({
          liid <- iid
          observeEvent(input[[paste0("del_item_", liid)]], {
            db_checklist_items_delete(db, liid)
            reload(reload() + 1L)
          }, ignoreInit = TRUE)
        })
      })
      observeEvent(input[[paste0("add_item_", lid)]], {
        txt <- input[[paste0("item_txt_", lid)]]
        req(nchar(trimws(txt)) > 0)
        its <- db_checklist_items_list(db, lid)
        pos <- if (nrow(its) > 0) max(its$position) + 1L else 1L
        db_checklist_items_insert(db, lid, trimws(txt), pos)
        shiny::updateTextInput(session, paste0("item_txt_", lid), value = "")
        reload(reload() + 1L)
      }, ignoreInit = TRUE)
    })

    observeEvent(input$add_list, {
      req(nchar(trimws(input$new_name)) > 0)
      db_checklists_insert(db, trimws(input$new_name), input$new_scope)
      shiny::updateTextInput(session, "new_name", value = "")
      reload(reload() + 1L)
    })
  })
}