adqs <- qs %>%
  # Add ADSL variables
  derive_vars_merged(
    dataset_add = adsl,
    new_vars = exprs(TRTSDT, DTHCAUS),
    by_vars = exprs(STUDYID, USUBJID)
  ) %>%
  # Add analysis parameter variables
  mutate(
    PARAMCD = QSTESTCD,
    PARAM = QSTEST,
    PARCAT1 = QSCAT,
    AVALC = QSORRES,
    AVAL = QSSTRESN
  ) %>%
  # Add timing variables
  derive_vars_dt(new_vars_prefix = "A", dtc = QSDTC) %>%
  derive_vars_dy(reference_date = TRTSDT, source_vars = exprs(ADT)) %>%
  mutate(
    AVISIT = if_else(ADT <= TRTSDT, "BASELINE", VISIT),
    AVISITN = if_else(ADT <= TRTSDT, 0, VISITNUM)
  )

adgad7 <- adqs %>%
  # Select records to keep in the GAD-7 ADaM
  filter(PARCAT1 == "GAD-7 V2") %>%
  derive_summary_records(
    dataset = .,
    dataset_add = .,
    by_vars = exprs(STUDYID, USUBJID, AVISIT, ADT, ADY, TRTSDT, DTHCAUS),
    # Select records contributing to total score
    filter_add = str_detect(PARAMCD, "GAD020[1-7]"),
    set_values_to = exprs(
      AVAL = sum(AVAL, na.rm = TRUE),
      PARAMCD = "GAD02TS",
      PARAM = "GAD02-Total Score - Analysis"
    )
  )

adgdssf <- adqs %>%
  # Select records to keep in the GDS-SF ADaM
  filter(PARCAT1 == "GDS SHORT FORM") %>%
  derive_summary_records(
    dataset = .,
    dataset_add = .,
    by_vars = exprs(STUDYID, USUBJID, AVISIT, ADT, ADY, TRTSDT, DTHCAUS),
    # Select records contributing to total score
    filter_add = str_detect(PARAMCD, "GDS02[01][0-9]"),
    set_values_to = exprs(
      AVAL = compute_scale(
        AVAL,
        source_range = c(0, 1),
        target_range = c(0, 15),
        min_n = 10
      ) %>%
        ceiling(),
      PARAMCD = "GDS02TS",
      PARAM = "GDS02- Total Score - Analysis"
    )
  )

adgdssf <- adgdssf %>%
  # Flag baseline records (last before treatement start)
  restrict_derivation(
    derivation = derive_var_extreme_flag,
    args = params(
      by_vars = exprs(STUDYID, USUBJID, PARAMCD),
      order = exprs(ADT),
      new_var = ABLFL,
      mode = "last"
    ),
    filter = !is.na(AVAL) & ADT <= TRTSDT
  ) %>%
  # Derive baseline and change from baseline variables
  derive_var_base(
    by_vars = exprs(STUDYID, USUBJID, PARAMCD),
    source_var = AVAL,
    new_var = BASE
  ) %>%
  # Calculate CHG for post-baseline records
  # The decision on how to populate pre-baseline and baseline values of CHG is left to producer choice
  restrict_derivation(
    derivation = derive_var_chg,
    filter = AVISITN > 0
  ) %>%
  # Calculate PCHG for post-baseline records
  # The decision on how to populate pre-baseline and baseline values of PCHG is left to producer choice
  restrict_derivation(
    derivation = derive_var_pchg,
    filter = AVISITN > 0
  ) %>%
  # Derive sequence number
  derive_var_obs_number(
    by_vars = exprs(STUDYID, USUBJID),
    order = exprs(PARAMCD, ADT),
    check_type = "error"
  )

# Create AVALCATx lookup table
avalcat_lookup <- exprs(
  ~PARAMCD, ~condition, ~AVALCAT1, ~AVALCAT1N,
  "GDS02TS", AVAL <= 5, "Normal", 0L,
  "GDS02TS", AVAL <= 10 & AVAL > 5, "Possible Depression", 1L,
  "GDS02TS", AVAL > 10, "Likely Depression", 2L
)
# Create CHGCAT1 lookup table
chgcat_lookup <- exprs(
  ~condition, ~CHGCAT1,
  AVALCAT1N > BASECA1N, "WORSENED",
  AVALCAT1N == BASECA1N, "NO CHANGE",
  AVALCAT1N < BASECA1N, "IMPROVED"
)

adgdssf <- adgdssf %>%
  derive_vars_cat(
    definition = avalcat_lookup,
    by_vars = exprs(PARAMCD)
  ) %>%
  derive_var_base(
    by_vars = exprs(STUDYID, USUBJID, PARAMCD),
    source_var = AVALCAT1,
    new_var = BASECAT1
  ) %>%
  derive_var_base(
    by_vars = exprs(STUDYID, USUBJID, PARAMCD),
    source_var = AVALCAT1N,
    new_var = BASECA1N
  ) %>%
  derive_vars_cat(
    definition = chgcat_lookup
  )

# Define event
deterioration_event <- event_source(
  dataset_name = "adqs",
  filter = PARAMCD == "GDS02TS" & CHGCAT1 == "WORSENED",
  date = ADT,
  set_values_to = exprs(
    EVNTDESC = "DEPRESSION WORSENED",
    SRCDOM = "ADQS",
    SRCVAR = "ADT",
    SRCSEQ = ASEQ
  )
)

# Define censoring at last assessment
last_valid_assessment <- censor_source(
  dataset_name = "adqs",
  filter = PARAMCD == "GDS02TS" & !is.na(CHGCAT1),
  date = ADT,
  set_values_to = exprs(
    EVNTDESC = "LAST ASSESSMENT",
    SRCDOM = "ADQS",
    SRCVAR = "ADT",
    SRCSEQ = ASEQ
  )
)

# Define censoring at treatment start (for subjects without assessment)
start <- censor_source(
  dataset_name = "adsl",
  date = TRTSDT,
  set_values_to = exprs(
    EVNTDESC = "TREATMENT START",
    SRCDOM = "ADSL",
    SRCVAR = "TRTSDT"
  )
)

adgdstte <- derive_param_tte(
  dataset_adsl = adsl,
  source_datasets = list(adsl = adsl, adqs = adgdssf),
  start_date = TRTSDT,
  event_conditions = list(deterioration_event),
  censor_conditions = list(last_valid_assessment, start),
  set_values_to = exprs(
    PARAMCD = "TTDEPR",
    PARAM = "Time to depression"
  )
) %>%
  derive_vars_duration(
    new_var = AVAL,
    start_date = STARTDT,
    end_date = ADT
  )

adgdssf <- adgdssf %>%
  derive_var_joined_exist_flag(
    dataset_add = adgdssf,
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(ADT),
    new_var = CDETFL,
    join_vars = exprs(CHGCAT1, ADY),
    join_type = "after",
    filter_join = CHGCAT1 == "WORSENED" &
      CHGCAT1.join == "WORSENED" &
      ADY.join >= ADY + 7
  )

# Flagging deterioration at two consecutive assessments
adgdssf <- adgdssf %>%
  derive_var_joined_exist_flag(
    dataset_add = adgdssf,
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(ADT),
    new_var = CONDETFL,
    join_vars = exprs(CHGCAT1),
    join_type = "after",
    tmp_obs_nr_var = tmp_obs_nr,
    filter_join = CHGCAT1 == "WORSENED" &
      CHGCAT1.join == "WORSENED" &
      tmp_obs_nr.join == tmp_obs_nr + 1
  ) %>%
  # Flagging deterioration confirmed by
  # - a second deterioration at least 7 days later or
  # - deterioration at the last assessment and death due to progression
  derive_var_joined_exist_flag(
    .,
    dataset_add = .,
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(ADT),
    new_var = CDTDTHFL,
    join_vars = exprs(CHGCAT1, ADY),
    join_type = "all",
    tmp_obs_nr_var = tmp_obs_nr,
    filter_join = CHGCAT1 == "WORSENED" & (
      CHGCAT1.join == "WORSENED" & ADY.join >= ADY + 7 |
        tmp_obs_nr == max(tmp_obs_nr.join) & DTHCAUS == "PROGRESSIVE DISEASE")
  )

adgdssf <- adgdssf %>%
  derive_var_joined_exist_flag(
    dataset_add = adgdssf,
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(ADT),
    new_var = DEFDETFL,
    join_vars = exprs(CHGCAT1),
    join_type = "after",
    filter_join = CHGCAT1 == "WORSENED" & all(CHGCAT1.join == "WORSENED")
  )

adsp <- adqs %>%
  filter(PARCAT1 == "SLEEPING PROBLEMS") %>%
  derive_extreme_event(
    by_vars = exprs(USUBJID, AVISIT),
    tmp_event_nr_var = event_nr,
    order = exprs(event_nr, ADY, QSSEQ),
    mode = "first",
    events = list(
      event(
        condition = PARAMCD == "SP0101" & AVALC == "YES",
        set_values_to = exprs(
          AVALC = "No sleep",
          AVAL = 1
        )
      ),
      event(
        condition = PARAMCD == "SP0102" & AVALC == "YES",
        set_values_to = exprs(
          AVALC = "Waking up more than three times",
          AVAL = 2
        )
      ),
      event(
        condition = PARAMCD == "SP0103" & AVALC == "YES",
        set_values_to = exprs(
          AVALC = "More than 30 mins to fall asleep",
          AVAL = 3
        )
      ),
      event(
        condition = all(AVALC == "NO"),
        set_values_to = exprs(
          AVALC = "No sleeping problems",
          AVAL = 4
        )
      ),
      event(
        condition = TRUE,
        set_values_to = exprs(
          AVALC = "Missing",
          AVAL = 99
        )
      )
    ),
    set_values_to = exprs(
      PARAMCD = "SP01WSP",
      PARAM = "Worst Sleeping Problems"
    )
  )

adgdssf <- adgdssf %>%
  derive_summary_records(
    dataset_add = adgdssf,
    filter_add = str_detect(PARAMCD, "GDS02[01][0-9]"),
    by_vars = exprs(USUBJID, AVISIT),
    set_values_to = exprs(
      AVAL = sum(!is.na(AVAL)) / 15 >= 0.9,
      PARAMCD = "COMPL90P",
      PARAM = "Completed at least 90% of questions?",
      AVALC = if_else(AVAL == 1, "YES", "NO")
    )
  )

# Create dataset with expected visits and parameters (GDS0201 - GDS0215)
parm_visit_ref <- crossing(
  tribble(
    ~AVISIT,    ~AVISITN,
    "BASELINE",        0,
    "VISIT 2",         2,
    "VISIT 3",         3,
    "VISIT 4",         4,
    "VISIT 5",         5
  ),
  tibble(PARAMCD = sprintf("GDS02%02d", seq(1, 15)))
)

adgdssf <- adgdssf %>%
  derive_expected_records(
    dataset_ref = parm_visit_ref,
    by_vars = exprs(USUBJID),
    set_values_to = exprs(
      filled_in = 1
    )
  ) %>%
  derive_summary_records(
    dataset = .,
    dataset_add = .,
    filter_add = str_detect(PARAMCD, "GDS02[01][0-9]"),
    by_vars = exprs(USUBJID, AVISIT),
    set_values_to = exprs(
      AVAL = all(!is.na(AVAL)),
      PARAMCD = "COMPLALL",
      PARAM = "Completed all questions?",
      AVALC = if_else(AVAL == 1, "YES", "NO")
    )
  ) %>%
  filter(is.na(filled_in)) %>%
  select(-filled_in)