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    use anyhow::Context as _;

    use cargo_util_schemas::manifest::PackageName;

    use crate::util::restricted_names;
    use crate::CargoResult;
    use crate::GlobalContext;

    const DEFAULT_EDITION: crate::core::features::Edition =
        crate::core::features::Edition::LATEST_STABLE;
    const AUTO_FIELDS: &[&str] = &["autobins", "autoexamples", "autotests", "autobenches"];

    pub(super) fn expand_manifest(
        content: &str,
        path: &std::path::Path,
        gctx: &GlobalContext,
    ) -> CargoResult<String> {
        let source = split_source(content)?;
        if let Some(frontmatter) = source.frontmatter {
            match source.info {
                Some("cargo") | None => {}
                Some(other) => {
                    if let Some(remainder) = other.strip_prefix("cargo,") {
                        anyhow::bail!("cargo does not support frontmatter infostring attributes like `{remainder}` at this time")
                    } else {
                        anyhow::bail!("frontmatter infostring `{other}` is unsupported by cargo; specify `cargo` for embedding a manifest")
                    }
                }
            }

            // HACK: until rustc has native support for this syntax, we have to remove it from the
            // source file
            use std::fmt::Write as _;
            let hash = crate::util::hex::short_hash(&path.to_string_lossy());
            let mut rel_path = std::path::PathBuf::new();
            rel_path.push("target");
            rel_path.push(&hash[0..2]);
            rel_path.push(&hash[2..]);
            let target_dir = gctx.home().join(rel_path);
            let hacked_path = target_dir
                .join(
                    path.file_name()
                        .expect("always a name for embedded manifests"),
                )
                .into_path_unlocked();
            let mut hacked_source = String::new();
            if let Some(shebang) = source.shebang {
                writeln!(hacked_source, "{shebang}")?;
            }
            writeln!(hacked_source)?; // open
            for _ in 0..frontmatter.lines().count() {
                writeln!(hacked_source)?;
            }
            writeln!(hacked_source)?; // close
            writeln!(hacked_source, "{}", source.content)?;
            if let Some(parent) = hacked_path.parent() {
                cargo_util::paths::create_dir_all(parent)?;
            }
            cargo_util::paths::write_if_changed(&hacked_path, hacked_source)?;

            let manifest = expand_manifest_(&frontmatter, &hacked_path, gctx)
                .with_context(|| format!("failed to parse manifest at {}", path.display()))?;
            let manifest = toml::to_string_pretty(&manifest)?;
            Ok(manifest)
        } else {
            let frontmatter = "";
            let manifest = expand_manifest_(frontmatter, path, gctx)
                .with_context(|| format!("failed to parse manifest at {}", path.display()))?;
            let manifest = toml::to_string_pretty(&manifest)?;
            Ok(manifest)
        }
    }

    fn expand_manifest_(
        manifest: &str,
        path: &std::path::Path,
        gctx: &GlobalContext,
    ) -> CargoResult<toml::Table> {
        let mut manifest: toml::Table = toml::from_str(&manifest)?;

        for key in ["workspace", "lib", "bin", "example", "test", "bench"] {
            if manifest.contains_key(key) {
                anyhow::bail!("`{key}` is not allowed in embedded manifests")
            }
        }

        // Prevent looking for a workspace by `read_manifest_from_str`
        manifest.insert("workspace".to_owned(), toml::Table::new().into());

        let package = manifest
            .entry("package".to_owned())
            .or_insert_with(|| toml::Table::new().into())
            .as_table_mut()
            .ok_or_else(|| anyhow::format_err!("`package` must be a table"))?;
        for key in ["workspace", "build", "links"]
            .iter()
            .chain(AUTO_FIELDS.iter())
        {
            if package.contains_key(*key) {
                anyhow::bail!("`package.{key}` is not allowed in embedded manifests")
            }
        }
        // HACK: Using an absolute path while `hacked_path` is in use
        let bin_path = path.to_string_lossy().into_owned();
        let file_stem = path
            .file_stem()
            .ok_or_else(|| anyhow::format_err!("no file name"))?
            .to_string_lossy();
        let name = sanitize_name(file_stem.as_ref());
        let bin_name = name.clone();
        package
            .entry("name".to_owned())
            .or_insert(toml::Value::String(name));
        package.entry("edition".to_owned()).or_insert_with(|| {
            let _ = gctx.shell().warn(format_args!(
                "`package.edition` is unspecified, defaulting to `{}`",
                DEFAULT_EDITION
            ));
            toml::Value::String(DEFAULT_EDITION.to_string())
        });
        package
            .entry("build".to_owned())
            .or_insert_with(|| toml::Value::Boolean(false));
        for field in AUTO_FIELDS {
            package
                .entry(field.to_owned())
                .or_insert_with(|| toml::Value::Boolean(false));
        }

        let mut bin = toml::Table::new();
        bin.insert("name".to_owned(), toml::Value::String(bin_name));
        bin.insert("path".to_owned(), toml::Value::String(bin_path));
        manifest.insert(
            "bin".to_owned(),
            toml::Value::Array(vec![toml::Value::Table(bin)]),
        );

        let release = manifest
            .entry("profile".to_owned())
            .or_insert_with(|| toml::Value::Table(Default::default()))
            .as_table_mut()
            .ok_or_else(|| anyhow::format_err!("`profile` must be a table"))?
            .entry("release".to_owned())
            .or_insert_with(|| toml::Value::Table(Default::default()))
            .as_table_mut()
            .ok_or_else(|| anyhow::format_err!("`profile.release` must be a table"))?;
        release
            .entry("strip".to_owned())
            .or_insert_with(|| toml::Value::Boolean(true));

        Ok(manifest)
    }

    /// Ensure the package name matches the validation from `ops::cargo_new::check_name`
    fn sanitize_name(name: &str) -> String {
        let placeholder = if name.contains('_') {
            '_'
        } else {
            // Since embedded manifests only support `[[bin]]`s, prefer arrow-case as that is the
            // more common convention for CLIs
            '-'
        };

        let mut name = PackageName::sanitize(name, placeholder).into_inner();

        loop {
            if restricted_names::is_keyword(&name) {
                name.push(placeholder);
            } else if restricted_names::is_conflicting_artifact_name(&name) {
                // Being an embedded manifest, we always assume it is a `[[bin]]`
                name.push(placeholder);
            } else if name == "test" {
                name.push(placeholder);
            } else if restricted_names::is_windows_reserved(&name) {
                // Go ahead and be consistent across platforms
                name.push(placeholder);
            } else {
                break;
            }
        }

        name
    }

    struct Source<'s> {
        shebang: Option<&'s str>,
        info: Option<&'s str>,
        frontmatter: Option<String>,
        content: &'s str,
    }

    fn split_source(input: &str) -> CargoResult<Source<'_>> {
        let mut source = Source {
            shebang: None,
            info: None,
            frontmatter: None,
            content: input,
        };

        // See rust-lang/rust's compiler/rustc_lexer/src/lib.rs's `strip_shebang`
        // Shebang must start with `#!` literally, without any preceding whitespace.
        // For simplicity we consider any line starting with `#!` a shebang,
        // regardless of restrictions put on shebangs by specific platforms.
        if let Some(rest) = source.content.strip_prefix("#!") {
            // Ok, this is a shebang but if the next non-whitespace token is `[`,
            // then it may be valid Rust code, so consider it Rust code.
            if rest.trim_start().starts_with('[') {
                return Ok(source);
            }

            // No other choice than to consider this a shebang.
            let (shebang, content) = source
                .content
                .split_once('\n')
                .unwrap_or((source.content, ""));
            source.shebang = Some(shebang);
            source.content = content;
        }

        // Experiment: let us try which char works better
        let tick_char = source
            .content
            .chars()
            .filter(|c| ['`', '#', '-'].contains(c))
            .next()
            .unwrap_or('`');

        let tick_end = source
            .content
            .char_indices()
            .find_map(|(i, c)| (c != tick_char).then_some(i))
            .unwrap_or(source.content.len());
        let (fence_pattern, rest) = match tick_end {
            0 => {
                return Ok(source);
            }
            1 if tick_char == '#' => {
                // Attribute
                return Ok(source);
            }
            2 if tick_char == '#' => {
                return split_prefix_source(source, "##");
            }
            1 | 2 => {
                anyhow::bail!("found {tick_end} `{tick_char}` in rust frontmatter, expected at least 3")
            }
            _ => source.content.split_at(tick_end),
        };
        let (info, content) = rest.split_once("\n").unwrap_or((rest, ""));
        if !info.is_empty() {
            source.info = Some(info.trim_end());
        }
        source.content = content;

        let Some((frontmatter, content)) = source.content.split_once(fence_pattern) else {
            anyhow::bail!("no closing `{fence_pattern}` found for frontmatter");
        };
        source.frontmatter = Some(frontmatter.to_owned());
        source.content = content;

        let (line, content) = source
            .content
            .split_once("\n")
            .unwrap_or((source.content, ""));
        let line = line.trim();
        if !line.is_empty() {
            anyhow::bail!("unexpected trailing content on closing fence: `{line}`");
        }
        source.content = content;

        Ok(source)
    }

    fn split_prefix_source<'s>(mut source: Source<'s>, prefix: &str) -> CargoResult<Source<'s>> {
        let mut frontmatter = String::new();
        while let Some(rest) = source.content.strip_prefix(prefix) {
            if !rest.is_empty() && !rest.starts_with(' ') {
                anyhow::bail!("frontmatter must have a space between `##` and the content");
            }
            let (line, rest) = rest.split_once('\n').unwrap_or((rest, ""));
            frontmatter.push_str("  ");
            frontmatter.push_str(line);
            frontmatter.push('\n');
            source.content = rest;
        }
        source.frontmatter = Some(frontmatter);
        Ok(source)
    }

    #[cfg(test)]
    mod test_expand {
        use super::*;

        macro_rules! si {
            ($i:expr) => {{
                expand_manifest(
                    $i,
                    std::path::Path::new("/home/me/test.rs"),
                    &GlobalContext::default().unwrap(),
                )
                .unwrap_or_else(|err| panic!("{}", err))
            }};
        }

        #[test]
        fn test_default() {
            snapbox::assert_eq(
                r#"[[bin]]
    name = "test-"
    path = "/home/me/test.rs"

    [package]
    autobenches = false
    autobins = false
    autoexamples = false
    autotests = false
    build = false
    edition = "2021"
    name = "test-"

    [profile.release]
    strip = true

    [workspace]
    "#,
                si!(r#"fn main() {}"#),
            );
        }

        #[test]
        fn test_dependencies() {
            snapbox::assert_matches(
                r#"[[bin]]
    name = "test-"
    path = [..]

    [dependencies]
    time = "0.1.25"

    [package]
    autobenches = false
    autobins = false
    autoexamples = false
    autotests = false
    build = false
    edition = "2021"
    name = "test-"

    [profile.release]
    strip = true

    [workspace]
    "#,
                si!(r#"```cargo
    [dependencies]
    time="0.1.25"
    ```
    fn main() {}
    "#),
            );
        }

        #[test]
        fn test_no_infostring() {
            snapbox::assert_matches(
                r#"[[bin]]
    name = "test-"
    path = [..]

    [dependencies]
    time = "0.1.25"

    [package]
    autobenches = false
    autobins = false
    autoexamples = false
    autotests = false
    build = false
    edition = "2021"
    name = "test-"

    [profile.release]
    strip = true

    [workspace]
    "#,
                si!(r#"```
    [dependencies]
    time="0.1.25"
    ```
    fn main() {}
    "#),
            );
        }

        #[test]
        fn test_dash_fence() {
            snapbox::assert_matches(
                r#"[[bin]]
    name = "test-"
    path = [..]

    [dependencies]
    time = "0.1.25"

    [package]
    autobenches = false
    autobins = false
    autoexamples = false
    autotests = false
    build = false
    edition = "2021"
    name = "test-"

    [profile.release]
    strip = true

    [workspace]
    "#,
                si!(r#"---
    [dependencies]
    time="0.1.25"
    ---
    fn main() {}
    "#),
            );
        }

        #[test]
        fn test_hash_fence() {
            snapbox::assert_matches(
                r#"[[bin]]
    name = "test-"
    path = [..]

    [dependencies]
    time = "0.1.25"

    [package]
    autobenches = false
    autobins = false
    autoexamples = false
    autotests = false
    build = false
    edition = "2021"
    name = "test-"

    [profile.release]
    strip = true

    [workspace]
    "#,
                si!(r#"###
    [dependencies]
    time="0.1.25"
    ###
    fn main() {}
    "#),
            );
        }

        #[test]
        fn test_hash_prefix() {
            snapbox::assert_matches(
                r#"[[bin]]
    name = "test-"
    path = [..]

    [dependencies]
    time = "0.1.25"

    [package]
    autobenches = false
    autobins = false
    autoexamples = false
    autotests = false
    build = false
    edition = "2021"
    name = "test-"

    [profile.release]
    strip = true

    [workspace]
    "#,
                si!(r#"## [dependencies]
    ## time="0.1.25"
    fn main() {}
    "#),
            );
        }
    }