extract_data <- function(turn, type, convert = TRUE, needs_wrapper = FALSE) {
  is_json <- map_lgl(turn@contents, S7_inherits, ContentJson)
  n <- sum(is_json)
  if (n == 0) {
    cli::cli_abort("Data extraction failed: no JSON responses found.")
  }

  if (n > 1) {
    cli::cli_warn("Found {n} JSON response{?s}, using the first.")
  }

  json <- turn@contents[[which(is_json)[1]]]
  out <- json@parsed # might error

  if (needs_wrapper) {
    out <- out$wrapper
    type <- type@properties[[1]]
  }
  if (convert) {
    out <- convert_from_type(out, type)
  }
  out
}

# Tool-based structured output can't stream (#977)
uses_tool_structured_output <- function(provider, type) {
  if (S7_inherits(provider, ProviderAWSBedrock)) {
    TRUE
  } else if (S7_inherits(provider, ProviderAnthropic)) {
    !has_claude_structured_output(provider@model)
  } else {
    FALSE
  }
}

# OpenAI only works with objects, so we wrap and unwrap as needed
type_needs_wrapper <- function(type, provider) {
  S7_inherits(provider, ProviderOpenAICompatible) &&
    !(S7_inherits(type, TypeObject) || S7_inherits(type, TypeJsonSchema))
}
wrap_type_if_needed <- function(type, needs_wrapper = FALSE) {
  if (needs_wrapper) {
    type_object(wrapper = type)
  } else {
    type
  }
}

convert_from_type <- function(x, type) {
  if (is.null(x) && !type@required) {
    x
  } else if (S7_inherits(type, TypeArray)) {
    if (S7_inherits(type@items, TypeBasic)) {
      list_to_atomic(x, type@items@type)
    } else if (S7_inherits(type@items, TypeArray)) {
      lapply(x, function(y) convert_from_type(y, type@items))
    } else if (S7_inherits(type@items, TypeEnum)) {
      factor(as.character(x), levels = type@items@values)
    } else if (S7_inherits(type@items, TypeObject)) {
      if (type@items@additional_properties) {
        # don't convert to data frame, but put known properties first
        lapply(x, \(y) y[union(names(type@items@properties), names(y))])
      } else {
        cols <- lapply(names(type@items@properties), function(name) {
          vals <- lapply(x, function(y) y[[name]])
          convert_from_type(vals, type_array(type@items@properties[[name]]))
        })
        names(cols) <- names(type@items@properties)
        tibble::as_tibble(vctrs::new_data_frame(cols))
      }
    } else {
      x
    }
  } else if (S7_inherits(type, TypeObject)) {
    out <- lapply(names(type@properties), function(name) {
      convert_from_type(x[[name]], type@properties[[name]])
    })
    out <- set_names(out, names(type@properties))

    if (type@additional_properties) {
      extra_props <- setdiff(names(x), names(type@properties))
      out <- c(out, as.list(x[extra_props]))
    }
    out
  } else if (S7_inherits(type, TypeBasic)) {
    if (is.null(x)) {
      switch(
        type@type,
        boolean = NA,
        integer = NA_integer_,
        number = NA_real_,
        string = NA_character_,
        cli::cli_abort("Unknown type {type@type}", .internal = TRUE)
      )
    } else if (is.list(x) && length(x) == 1) {
      # Some models intermittently wrap scalars in a JSON array (#931)
      x[[1]]
    } else {
      x
    }
  } else if (S7_inherits(type, TypeEnum)) {
    if (is.null(x)) {
      NA_character_
    } else {
      as.character(x)
    }
  } else {
    x
  }
}

list_to_atomic <- function(x, type) {
  r_type <- switch(
    type,
    boolean = "logical",
    integer = "integer",
    number = "double",
    string = "character",
    cli::cli_abort("Unknown type {type}", .internal = TRUE)
  )

  if (length(x) == 0) {
    return(vector(r_type, 0))
  }

  types <- map_chr(x, typeof)
  if (r_type == "integer") {
    doubles <- which(types == "double")
    x[doubles] <- lapply(x[doubles], as.integer)
    types[doubles] <- "integer"
  } else if (r_type == "double") {
    integers <- which(types == "integer")
    x[integers] <- lapply(x[integers], as.double)
    types[integers] <- "double"
  }

  # silently replace incorrect types (incl NULLs) to NA
  wrong_type <- types != r_type
  x[wrong_type] <- list(`mode<-`(NA, r_type))

  # silently truncate incorrect lengths to 1
  x[lengths(x) != 1] <- lapply(x[lengths(x) != 1], \(x) x[1])

  unlist(x, use.names = FALSE, recursive = FALSE)
}
