wdl-engine 0.13.2

//! Implements the `read_object` function from the WDL standard library.

use futures::FutureExt;
use futures::future::BoxFuture;
use indexmap::IndexMap;
use itertools::EitherOrBoth;
use itertools::Itertools;
use tokio::fs;
use tokio::io::AsyncBufReadExt;
use tokio::io::BufReader;
use wdl_analysis::types::PrimitiveType;
use wdl_analysis::types::Type;
use wdl_ast::Diagnostic;
use wdl_grammar::lexer::v1::is_ident;

use super::CallContext;
use super::Callback;
use super::Function;
use super::Signature;
use crate::Object;
use crate::PrimitiveValue;
use crate::Value;
use crate::diagnostics::function_call_failed;
use crate::stdlib::download_file;

/// The name of the function defined in this file for use in diagnostics.
const FUNCTION_NAME: &str = "read_object";

/// Reads a tab-separated value (TSV) file representing the names and values of
/// the members of an Object.
///
/// There must be exactly two rows, and each row must have the same number of
/// elements, otherwise an error is raised.
///
/// Trailing end-of-line characters (\r and \n) are removed from each line.
///
/// The first row specifies the object member names. The names in the first row
/// must be unique; if there are any duplicate names, an error is raised.
///
/// The second row specifies the object member values corresponding to the names
/// in the first row. All of the Object's values are of type String.
///
/// https://github.com/openwdl/wdl/blob/wdl-1.2/SPEC.md#read_object
fn read_object(context: CallContext<'_>) -> BoxFuture<'_, Result<Value, Diagnostic>> {
    async move {
        debug_assert!(context.arguments.len() == 1);
        debug_assert!(context.return_type_eq(Type::Object));

        let path = context
            .coerce_argument(0, PrimitiveType::File)
            .unwrap_file();

        let file_path = download_file(context.transferer(), context.base_dir(), &path)
            .await
            .map_err(|e| function_call_failed(FUNCTION_NAME, e, context.arguments[0].span))?;

        let read_error = |e: std::io::Error| {
            function_call_failed(
                FUNCTION_NAME,
                format!(
                    "failed to read file `{path}`: {e}",
                    path = file_path.display()
                ),
                context.call_site,
            )
        };

        let expected_two_lines = || {
            function_call_failed(
                FUNCTION_NAME,
                format!("expected exactly two lines in file `{path}`"),
                context.call_site,
            )
        };

        let file = fs::File::open(&file_path).await.map_err(read_error)?;

        let mut lines = BufReader::new(file).lines();
        let names = lines
            .next_line()
            .await
            .map_err(read_error)?
            .ok_or_else(expected_two_lines)?;

        let values = lines
            .next_line()
            .await
            .map_err(read_error)?
            .ok_or_else(expected_two_lines)?;

        if lines.next_line().await.map_err(read_error)?.is_some() {
            return Err(expected_two_lines());
        }

        let mut members = IndexMap::new();
        for e in names.split('\t').zip_longest(values.split('\t')) {
            match e {
                EitherOrBoth::Both(name, value) => {
                    if !is_ident(name) {
                        return Err(function_call_failed(
                            FUNCTION_NAME,
                            format!(
                                "line 1 of file `{path}` contains invalid column name `{name}`: \
                                 column name must be a valid WDL identifier"
                            ),
                            context.call_site,
                        ));
                    }

                    if members
                        .insert(name.to_string(), PrimitiveValue::new_string(value).into())
                        .is_some()
                    {
                        return Err(function_call_failed(
                            FUNCTION_NAME,
                            format!(
                                "line 1 of file `{path}` contains duplicate column name `{name}`"
                            ),
                            context.call_site,
                        ));
                    }
                }
                EitherOrBoth::Left(_) | EitherOrBoth::Right(_) => {
                    return Err(function_call_failed(
                        FUNCTION_NAME,
                        format!(
                            "line 2 of file `{path}` does not contain the expected number of \
                             columns"
                        ),
                        context.call_site,
                    ));
                }
            }
        }

        Ok(Object::new(members).into())
    }
    .boxed()
}

/// Gets the function describing `read_object`.
pub const fn descriptor() -> Function {
    Function::new(
        const {
            &[Signature::new(
                "(file: File) -> Object",
                Callback::Async(read_object),
            )]
        },
    )
}

#[cfg(test)]
mod test {
    use pretty_assertions::assert_eq;
    use wdl_ast::version::V1;

    use crate::v1::test::TestEnv;
    use crate::v1::test::eval_v1_expr;

    #[tokio::test]
    async fn read_object() {
        let env = TestEnv::default();
        env.write_file("empty.tsv", "");
        env.write_file("object.tsv", "foo\tbar\nbaz\tqux");
        env.write_file("too-many-lines.tsv", "foo\tbar\nbaz\tqux\njam\tcakes\n");
        env.write_file("too-few-lines.tsv", "foo\tbar\n");
        env.write_file("too-few-columns.tsv", "foo\tbar\nbaz\n");
        env.write_file("too-many-columns.tsv", "foo\tbar\nbaz\tqux\twrong\n");
        env.write_file("duplicate.tsv", "foo\tbar\tfoo\nbaz\tqux\tfoo\n");
        env.write_file("invalid-name.tsv", "foo\ttask\tfoo\nbaz\tqux\tfoo\n");

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('empty.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: expected exactly two lines in file `empty.tsv`"
        );

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('too-many-lines.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: expected exactly two lines in file \
             `too-many-lines.tsv`"
        );

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('too-few-lines.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: expected exactly two lines in file \
             `too-few-lines.tsv`"
        );

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('too-many-columns.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: line 2 of file `too-many-columns.tsv` does \
             not contain the expected number of columns"
        );

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('too-few-columns.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: line 2 of file `too-few-columns.tsv` does not \
             contain the expected number of columns"
        );

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('duplicate.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: line 1 of file `duplicate.tsv` contains \
             duplicate column name `foo`"
        );

        let diagnostic = eval_v1_expr(&env, V1::Two, "read_object('invalid-name.tsv')")
            .await
            .unwrap_err();
        assert_eq!(
            diagnostic.message(),
            "call to function `read_object` failed: line 1 of file `invalid-name.tsv` contains \
             invalid column name `task`: column name must be a valid WDL identifier"
        );

        for file in ["object.tsv", "https://example.com/object.tsv"] {
            let value = eval_v1_expr(&env, V1::Two, &format!("read_object('{file}')"))
                .await
                .unwrap();
            assert_eq!(
                value.unwrap_object().to_string(),
                r#"object {foo: "baz", bar: "qux"}"#
            );
        }
    }
}