runmat-runtime 0.5.0

//! MATLAB-compatible `copyfile` builtin for RunMat.

use runmat_filesystem as vfs;
use std::io;
use std::path::{Path, PathBuf};

use glob::Pattern;
use runmat_builtins::{
    BuiltinCompletionPolicy, BuiltinDescriptor, BuiltinErrorDescriptor, BuiltinOutputMode,
    BuiltinParamArity, BuiltinParamDescriptor, BuiltinParamType, BuiltinSignatureDescriptor,
    CharArray, Value,
};
use runmat_macros::runtime_builtin;

use crate::builtins::common::fs::{contains_wildcards, expand_user_path};
use crate::builtins::common::spec::{
    BroadcastSemantics, BuiltinFusionSpec, BuiltinGpuSpec, ConstantStrategy, GpuOpKind,
    ReductionNaN, ResidencyPolicy, ShapeRequirements,
};
use crate::{build_runtime_error, gather_if_needed_async, BuiltinResult, RuntimeError};

#[runmat_macros::register_gpu_spec(builtin_path = "crate::builtins::io::repl_fs::copyfile")]
pub const GPU_SPEC: BuiltinGpuSpec = BuiltinGpuSpec {
    name: "copyfile",
    op_kind: GpuOpKind::Custom("io"),
    supported_precisions: &[],
    broadcast: BroadcastSemantics::None,
    provider_hooks: &[],
    constant_strategy: ConstantStrategy::InlineLiteral,
    residency: ResidencyPolicy::GatherImmediately,
    nan_mode: ReductionNaN::Include,
    two_pass_threshold: None,
    workgroup_size: None,
    accepts_nan_mode: false,
    notes:
        "Host-only filesystem operation. GPU-resident path and flag arguments are gathered automatically before performing the copy.",
};

#[runmat_macros::register_fusion_spec(builtin_path = "crate::builtins::io::repl_fs::copyfile")]
pub const FUSION_SPEC: BuiltinFusionSpec = BuiltinFusionSpec {
    name: "copyfile",
    shape: ShapeRequirements::Any,
    constant_strategy: ConstantStrategy::InlineLiteral,
    elementwise: None,
    reduction: None,
    emits_nan: false,
    notes:
        "Filesystem side effects materialise immediately; metadata is registered for completeness.",
};

const BUILTIN_NAME: &str = "copyfile";

const COPYFILE_OUTPUT_STATUS: [BuiltinParamDescriptor; 1] = [BuiltinParamDescriptor {
    name: "status",
    ty: BuiltinParamType::NumericScalar,
    arity: BuiltinParamArity::Required,
    default: None,
    description: "1 on success, 0 when copy fails.",
}];
const COPYFILE_OUTPUT_STATUS_MSG_MSGID: [BuiltinParamDescriptor; 3] = [
    BuiltinParamDescriptor {
        name: "status",
        ty: BuiltinParamType::NumericScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "1 on success, 0 when copy fails.",
    },
    BuiltinParamDescriptor {
        name: "msg",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "Diagnostic message for failures.",
    },
    BuiltinParamDescriptor {
        name: "msgID",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "Stable diagnostic identifier string.",
    },
];
const COPYFILE_INPUTS_SOURCE_DEST: [BuiltinParamDescriptor; 2] = [
    BuiltinParamDescriptor {
        name: "source",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "Source file/folder path or wildcard pattern.",
    },
    BuiltinParamDescriptor {
        name: "destination",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "Destination path.",
    },
];
const COPYFILE_INPUTS_SOURCE_DEST_FLAG: [BuiltinParamDescriptor; 3] = [
    BuiltinParamDescriptor {
        name: "source",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "Source file/folder path or wildcard pattern.",
    },
    BuiltinParamDescriptor {
        name: "destination",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: None,
        description: "Destination path.",
    },
    BuiltinParamDescriptor {
        name: "flag",
        ty: BuiltinParamType::StringScalar,
        arity: BuiltinParamArity::Required,
        default: Some("\"f\""),
        description: "Overwrite flag; only \"f\" is accepted.",
    },
];
const COPYFILE_SIGNATURES: [BuiltinSignatureDescriptor; 4] = [
    BuiltinSignatureDescriptor {
        label: "status = copyfile(source, destination)",
        inputs: &COPYFILE_INPUTS_SOURCE_DEST,
        outputs: &COPYFILE_OUTPUT_STATUS,
    },
    BuiltinSignatureDescriptor {
        label: "status = copyfile(source, destination, flag)",
        inputs: &COPYFILE_INPUTS_SOURCE_DEST_FLAG,
        outputs: &COPYFILE_OUTPUT_STATUS,
    },
    BuiltinSignatureDescriptor {
        label: "[status, msg, msgID] = copyfile(source, destination)",
        inputs: &COPYFILE_INPUTS_SOURCE_DEST,
        outputs: &COPYFILE_OUTPUT_STATUS_MSG_MSGID,
    },
    BuiltinSignatureDescriptor {
        label: "[status, msg, msgID] = copyfile(source, destination, flag)",
        inputs: &COPYFILE_INPUTS_SOURCE_DEST_FLAG,
        outputs: &COPYFILE_OUTPUT_STATUS_MSG_MSGID,
    },
];
const COPYFILE_ERROR_NOT_ENOUGH_INPUTS: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.NOT_ENOUGH_INPUTS",
    identifier: Some("RunMat:copyfile:NotEnoughInputs"),
    when: "Fewer than two input arguments are provided.",
    message: "copyfile: not enough input arguments",
};
const COPYFILE_ERROR_TOO_MANY_INPUTS: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.TOO_MANY_INPUTS",
    identifier: Some("RunMat:copyfile:TooManyInputs"),
    when: "More than three input arguments are provided.",
    message: "copyfile: too many input arguments",
};
const COPYFILE_ERROR_SOURCE_ARG: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.SOURCE_ARG",
    identifier: Some("RunMat:copyfile:SourceArgType"),
    when: "Source argument is not a character vector or string scalar.",
    message: "copyfile: source must be a character vector or string scalar",
};
const COPYFILE_ERROR_DEST_ARG: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.DEST_ARG",
    identifier: Some("RunMat:copyfile:DestinationArgType"),
    when: "Destination argument is not a character vector or string scalar.",
    message: "copyfile: destination must be a character vector or string scalar",
};
const COPYFILE_ERROR_FLAG_ARG: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.FLAG_ARG",
    identifier: Some("RunMat:copyfile:FlagArgType"),
    when: "Flag argument is not the scalar character 'f'.",
    message: "copyfile: flag must be the character 'f' supplied as a char vector or string scalar",
};
const COPYFILE_RESULT_OS_ERROR: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.OS_ERROR",
    identifier: Some("RunMat:copyfile:OSError"),
    when: "Filesystem copy operation fails.",
    message: "copyfile: unable to copy",
};
const COPYFILE_RESULT_SOURCE_NOT_FOUND: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.SOURCE_NOT_FOUND",
    identifier: Some("RunMat:copyfile:FileDoesNotExist"),
    when: "Source path or wildcard match does not exist.",
    message: "copyfile: source not found",
};
const COPYFILE_RESULT_DEST_EXISTS: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.DEST_EXISTS",
    identifier: Some("RunMat:copyfile:DestinationExists"),
    when: "Destination already exists and overwrite is not requested.",
    message: "copyfile: destination already exists",
};
const COPYFILE_RESULT_DEST_MISSING: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.DEST_MISSING",
    identifier: Some("RunMat:copyfile:DestinationNotFound"),
    when: "Destination directory is missing for wildcard source copies.",
    message: "copyfile: destination folder not found",
};
const COPYFILE_RESULT_DEST_NOT_DIR: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.DEST_NOT_DIR",
    identifier: Some("RunMat:copyfile:DestinationNotDirectory"),
    when: "Destination must be a directory for wildcard or directory copy modes.",
    message: "copyfile: destination is not a directory",
};
const COPYFILE_RESULT_EMPTY_SOURCE: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.EMPTY_SOURCE",
    identifier: Some("RunMat:copyfile:EmptySource"),
    when: "Source path is empty.",
    message: "Source file or folder name must not be empty.",
};
const COPYFILE_RESULT_EMPTY_DEST: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.EMPTY_DEST",
    identifier: Some("RunMat:copyfile:EmptyDestination"),
    when: "Destination path is empty.",
    message: "Destination file or folder name must not be empty.",
};
const COPYFILE_RESULT_PATTERN_ERROR: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.PATTERN_ERROR",
    identifier: Some("RunMat:copyfile:InvalidPattern"),
    when: "Source wildcard pattern is invalid.",
    message: "copyfile: invalid source pattern",
};
const COPYFILE_RESULT_SAME_PATH: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
    code: "RM.COPYFILE.SAME_PATH",
    identifier: Some("RunMat:copyfile:SourceEqualsDestination"),
    when: "Source and destination resolve to the same path.",
    message: "copyfile: source and destination are the same",
};
const COPYFILE_ERRORS: [BuiltinErrorDescriptor; 14] = [
    COPYFILE_ERROR_NOT_ENOUGH_INPUTS,
    COPYFILE_ERROR_TOO_MANY_INPUTS,
    COPYFILE_ERROR_SOURCE_ARG,
    COPYFILE_ERROR_DEST_ARG,
    COPYFILE_ERROR_FLAG_ARG,
    COPYFILE_RESULT_OS_ERROR,
    COPYFILE_RESULT_SOURCE_NOT_FOUND,
    COPYFILE_RESULT_DEST_EXISTS,
    COPYFILE_RESULT_DEST_MISSING,
    COPYFILE_RESULT_DEST_NOT_DIR,
    COPYFILE_RESULT_EMPTY_SOURCE,
    COPYFILE_RESULT_EMPTY_DEST,
    COPYFILE_RESULT_PATTERN_ERROR,
    COPYFILE_RESULT_SAME_PATH,
];
pub const COPYFILE_DESCRIPTOR: BuiltinDescriptor = BuiltinDescriptor {
    signatures: &COPYFILE_SIGNATURES,
    output_mode: BuiltinOutputMode::ByRequestedOutputCount,
    completion_policy: BuiltinCompletionPolicy::Public,
    errors: &COPYFILE_ERRORS,
};

fn copyfile_error_row(error: &'static BuiltinErrorDescriptor) -> RuntimeError {
    let mut builder = build_runtime_error(error.message).with_builtin(BUILTIN_NAME);
    if let Some(identifier) = error.identifier {
        builder = builder.with_identifier(identifier);
    }
    builder.build()
}

fn copyfile_error(message: impl Into<String>) -> RuntimeError {
    build_runtime_error(message)
        .with_builtin(BUILTIN_NAME)
        .build()
}

fn map_control_flow(err: RuntimeError) -> RuntimeError {
    let identifier = err.identifier().map(str::to_string);
    let mut builder = build_runtime_error(format!("{BUILTIN_NAME}: {}", err.message()))
        .with_builtin(BUILTIN_NAME)
        .with_source(err);
    if let Some(identifier) = identifier {
        builder = builder.with_identifier(identifier);
    }
    builder.build()
}

#[runtime_builtin(
    name = "copyfile",
    category = "io/repl_fs",
    summary = "Copy files or folders.",
    keywords = "copyfile,copy file,copy folder,filesystem,status,message,messageid,force,overwrite",
    accel = "cpu",
    suppress_auto_output = true,
    type_resolver(crate::builtins::io::type_resolvers::copyfile_type),
    descriptor(crate::builtins::io::repl_fs::copyfile::COPYFILE_DESCRIPTOR),
    builtin_path = "crate::builtins::io::repl_fs::copyfile"
)]
async fn copyfile_builtin(args: Vec<Value>) -> crate::BuiltinResult<Value> {
    let eval = evaluate(&args).await?;
    if let Some(out_count) = crate::output_count::current_output_count() {
        if out_count == 0 {
            return Ok(Value::OutputList(Vec::new()));
        }
        return Ok(crate::output_count::output_list_with_padding(
            out_count,
            eval.outputs(),
        ));
    }
    Ok(eval.first_output())
}

/// Evaluate `copyfile` once and expose all outputs.
pub async fn evaluate(args: &[Value]) -> BuiltinResult<CopyfileResult> {
    let gathered = gather_arguments(args).await?;
    match gathered.len() {
        0 | 1 => Err(copyfile_error_row(&COPYFILE_ERROR_NOT_ENOUGH_INPUTS)),
        2 => copy_operation(&gathered[0], &gathered[1], false).await,
        3 => {
            let force = parse_force_flag(&gathered[2])?;
            copy_operation(&gathered[0], &gathered[1], force).await
        }
        _ => Err(copyfile_error_row(&COPYFILE_ERROR_TOO_MANY_INPUTS)),
    }
}

#[derive(Debug, Clone)]
pub struct CopyfileResult {
    status: f64,
    message: String,
    message_id: String,
}

impl CopyfileResult {
    fn success() -> Self {
        Self {
            status: 1.0,
            message: String::new(),
            message_id: String::new(),
        }
    }

    fn failure(message: String, error: &'static BuiltinErrorDescriptor) -> Self {
        Self {
            status: 0.0,
            message,
            message_id: message_identifier(error).to_string(),
        }
    }

    fn empty_source() -> Self {
        Self::failure(
            COPYFILE_RESULT_EMPTY_SOURCE.message.to_string(),
            &COPYFILE_RESULT_EMPTY_SOURCE,
        )
    }

    fn empty_destination() -> Self {
        Self::failure(
            COPYFILE_RESULT_EMPTY_DEST.message.to_string(),
            &COPYFILE_RESULT_EMPTY_DEST,
        )
    }

    fn source_not_found(display: &str) -> Self {
        Self::failure(
            format!("Source \"{}\" does not exist.", display),
            &COPYFILE_RESULT_SOURCE_NOT_FOUND,
        )
    }

    fn destination_exists(display: &str) -> Self {
        Self::failure(
            format!(
                "Cannot copy to \"{}\": destination already exists.",
                display
            ),
            &COPYFILE_RESULT_DEST_EXISTS,
        )
    }

    fn destination_missing(display: &str) -> Self {
        Self::failure(
            format!(
                "Destination folder \"{}\" must exist when copying multiple sources.",
                display
            ),
            &COPYFILE_RESULT_DEST_MISSING,
        )
    }

    fn destination_not_directory(display: &str) -> Self {
        Self::failure(
            format!("Destination \"{}\" must refer to a folder.", display),
            &COPYFILE_RESULT_DEST_NOT_DIR,
        )
    }

    fn same_path(display: &str) -> Self {
        Self::failure(
            format!("Cannot copy \"{}\" onto itself.", display),
            &COPYFILE_RESULT_SAME_PATH,
        )
    }

    fn glob_pattern_error(pattern: &str, err: &str) -> Self {
        Self::failure(
            format!("Invalid source pattern \"{}\": {}", pattern, err),
            &COPYFILE_RESULT_PATTERN_ERROR,
        )
    }

    fn os_error(source: &str, target: &str, err: &io::Error) -> Self {
        Self::failure(
            format!("Unable to copy \"{}\" to \"{}\": {}", source, target, err),
            &COPYFILE_RESULT_OS_ERROR,
        )
    }

    pub fn first_output(&self) -> Value {
        Value::Num(self.status)
    }

    pub fn outputs(&self) -> Vec<Value> {
        vec![
            Value::Num(self.status),
            char_array_value(&self.message),
            char_array_value(&self.message_id),
        ]
    }

    #[cfg(test)]
    pub(crate) fn status(&self) -> f64 {
        self.status
    }

    #[cfg(test)]
    pub(crate) fn message(&self) -> &str {
        &self.message
    }

    #[cfg(test)]
    pub(crate) fn message_id(&self) -> &str {
        &self.message_id
    }
}

async fn copy_operation(
    source: &Value,
    destination: &Value,
    force: bool,
) -> BuiltinResult<CopyfileResult> {
    let source_raw = extract_path(source, &COPYFILE_ERROR_SOURCE_ARG)?;
    if source_raw.is_empty() {
        return Ok(CopyfileResult::empty_source());
    }

    let destination_raw = extract_path(destination, &COPYFILE_ERROR_DEST_ARG)?;
    if destination_raw.is_empty() {
        return Ok(CopyfileResult::empty_destination());
    }

    let source_expanded = expand_user_path(&source_raw, "copyfile").map_err(copyfile_error)?;
    let destination_expanded =
        expand_user_path(&destination_raw, "copyfile").map_err(copyfile_error)?;

    if contains_wildcards(&source_expanded) {
        Ok(copy_with_pattern(&source_expanded, &destination_expanded, force).await)
    } else {
        Ok(copy_single_source(&source_expanded, &destination_expanded, force).await)
    }
}

async fn copy_single_source(source: &str, destination: &str, force: bool) -> CopyfileResult {
    let source_path = PathBuf::from(source);
    let source_meta = match vfs::metadata_async(&source_path).await {
        Ok(meta) => meta,
        Err(_) => return CopyfileResult::source_not_found(source),
    };
    let source_display = path_to_display(&source_path);

    let destination_path = PathBuf::from(destination);
    if same_physical_path(&source_path, &destination_path).await {
        return CopyfileResult::same_path(&source_display);
    }

    let destination_meta = vfs::metadata_async(&destination_path).await.ok();
    let mut target_path = destination_path.clone();
    let mut remove_target = false;
    let mut remove_is_dir = false;

    if let Some(meta) = &destination_meta {
        if meta.is_dir() {
            let Some(name) = source_path.file_name() else {
                return CopyfileResult::os_error(
                    source,
                    destination,
                    &io::Error::other("Cannot determine source file name"),
                );
            };
            target_path = destination_path.join(name);
            if same_physical_path(&source_path, &target_path).await {
                return CopyfileResult::same_path(&source_display);
            }
            if source_meta.is_dir() && is_descendant(&source_path, &target_path).await {
                return CopyfileResult::failure(
                    "Cannot copy a folder into one of its descendants.".to_string(),
                    &COPYFILE_RESULT_OS_ERROR,
                );
            }
            match vfs::metadata_async(&target_path).await {
                Ok(existing) => {
                    if !force {
                        return CopyfileResult::destination_exists(&path_to_display(&target_path));
                    }
                    remove_target = true;
                    remove_is_dir = existing.is_dir();
                }
                Err(err) => {
                    if err.kind() != io::ErrorKind::NotFound {
                        return CopyfileResult::os_error(
                            source,
                            &path_to_display(&target_path),
                            &err,
                        );
                    }
                }
            }
        } else {
            if source_meta.is_dir() {
                return CopyfileResult::destination_not_directory(destination);
            }
            if !force {
                return CopyfileResult::destination_exists(destination);
            }
            remove_target = true;
            remove_is_dir = false;
        }
    } else if source_meta.is_dir() {
        // When copying a directory to a new path, ensure we don't copy into a child of itself.
        if is_descendant(&source_path, &destination_path).await {
            return CopyfileResult::failure(
                "Cannot copy a folder into one of its descendants.".to_string(),
                &COPYFILE_RESULT_OS_ERROR,
            );
        }
    }

    let target_display = path_to_display(&target_path);
    let plan = vec![CopyPlanEntry::new(
        source_path,
        source_display.clone(),
        target_path,
        target_display,
        source_meta.is_dir(),
        remove_target,
        remove_is_dir,
    )];

    match execute_plan(&plan).await {
        Ok(()) => CopyfileResult::success(),
        Err(err) => CopyfileResult::os_error(&err.source_display, &err.target_display, &err.error),
    }
}

async fn copy_with_pattern(pattern: &str, destination: &str, force: bool) -> CopyfileResult {
    let pattern_path = Path::new(pattern);
    let (base_dir, name_pattern) = match pattern_path.file_name() {
        Some(name) => (
            pattern_path.parent().unwrap_or_else(|| Path::new(".")),
            name,
        ),
        None => {
            return CopyfileResult::glob_pattern_error(pattern, "pattern has no file name");
        }
    };
    let matcher = match Pattern::new(&name_pattern.to_string_lossy()) {
        Ok(matcher) => matcher,
        Err(err) => return CopyfileResult::glob_pattern_error(pattern, err.msg),
    };

    let mut matches = Vec::new();
    let entries = match vfs::read_dir_async(base_dir).await {
        Ok(entries) => entries,
        Err(err) => {
            let display = path_to_display(base_dir);
            return CopyfileResult::os_error(&display, destination, &err);
        }
    };

    for entry in entries {
        let file_name = entry.file_name().to_string_lossy();
        if matcher.matches(&file_name) {
            matches.push(entry.path().to_path_buf());
        }
    }

    if matches.is_empty() {
        return CopyfileResult::source_not_found(pattern);
    }

    let destination_path = PathBuf::from(destination);
    let destination_meta = match vfs::metadata_async(&destination_path).await {
        Ok(meta) => meta,
        Err(_) => return CopyfileResult::destination_missing(destination),
    };

    if !destination_meta.is_dir() {
        return CopyfileResult::destination_not_directory(destination);
    }

    let mut plan = Vec::with_capacity(matches.len());
    for source_path in matches {
        let display_source = path_to_display(&source_path);
        let meta = match vfs::metadata_async(&source_path).await {
            Ok(meta) => meta,
            Err(_) => return CopyfileResult::source_not_found(&display_source),
        };
        let Some(name) = source_path.file_name() else {
            return CopyfileResult::os_error(
                &display_source,
                destination,
                &io::Error::other("Cannot determine source name"),
            );
        };
        let target_path = destination_path.join(name);
        if same_physical_path(&source_path, &target_path).await {
            return CopyfileResult::same_path(&display_source);
        }
        let target_display = path_to_display(&target_path);
        match vfs::metadata_async(&target_path).await {
            Ok(existing) => {
                if !force {
                    return CopyfileResult::destination_exists(&target_display);
                }
                plan.push(CopyPlanEntry::new(
                    source_path.clone(),
                    display_source.clone(),
                    target_path.clone(),
                    target_display,
                    meta.is_dir(),
                    true,
                    existing.is_dir(),
                ));
            }
            Err(err) => {
                if err.kind() != io::ErrorKind::NotFound {
                    return CopyfileResult::os_error(&display_source, &target_display, &err);
                }
                plan.push(CopyPlanEntry::new(
                    source_path.clone(),
                    display_source,
                    target_path.clone(),
                    target_display,
                    meta.is_dir(),
                    false,
                    false,
                ));
            }
        }
    }

    if plan.is_empty() {
        return CopyfileResult::success();
    }

    match execute_plan(&plan).await {
        Ok(()) => CopyfileResult::success(),
        Err(err) => CopyfileResult::os_error(&err.source_display, &err.target_display, &err.error),
    }
}

#[derive(Debug, Clone)]
struct CopyPlanEntry {
    source_path: PathBuf,
    source_display: String,
    target_path: PathBuf,
    target_display: String,
    source_is_dir: bool,
    remove_target: bool,
    remove_is_dir: bool,
}

impl CopyPlanEntry {
    fn new(
        source_path: PathBuf,
        source_display: String,
        target_path: PathBuf,
        target_display: String,
        source_is_dir: bool,
        remove_target: bool,
        remove_is_dir: bool,
    ) -> Self {
        Self {
            source_path,
            source_display,
            target_path,
            target_display,
            source_is_dir,
            remove_target,
            remove_is_dir,
        }
    }
}

struct CopyError {
    source_display: String,
    target_display: String,
    error: io::Error,
}

async fn execute_plan(plan: &[CopyPlanEntry]) -> Result<(), CopyError> {
    for entry in plan {
        if entry.remove_target {
            let result = if entry.remove_is_dir {
                vfs::remove_dir_all_async(&entry.target_path).await
            } else {
                vfs::remove_file_async(&entry.target_path).await
            };
            if let Err(err) = result {
                if err.kind() != io::ErrorKind::NotFound {
                    return Err(CopyError {
                        source_display: entry.source_display.clone(),
                        target_display: entry.target_display.clone(),
                        error: err,
                    });
                }
            }
        }

        if let Err(err) =
            copy_path(&entry.source_path, &entry.target_path, entry.source_is_dir).await
        {
            return Err(CopyError {
                source_display: entry.source_display.clone(),
                target_display: entry.target_display.clone(),
                error: err,
            });
        }
    }

    Ok(())
}

async fn copy_path(source: &Path, destination: &Path, is_directory: bool) -> io::Result<()> {
    if is_directory {
        copy_directory_recursive(source, destination).await
    } else {
        copy_file_to_path(source, destination).await
    }
}

#[async_recursion::async_recursion(?Send)]
async fn copy_directory_recursive(source: &Path, destination: &Path) -> io::Result<()> {
    ensure_parent_exists(destination).await?;

    match vfs::metadata_async(destination).await {
        Ok(meta) => {
            if !meta.is_dir() {
                return Err(io::Error::new(
                    io::ErrorKind::AlreadyExists,
                    "Destination exists and is not a directory",
                ));
            }
        }
        Err(err) => {
            if err.kind() != io::ErrorKind::NotFound {
                return Err(err);
            }
            vfs::create_dir_all_async(destination).await?;
        }
    }

    if let Ok(metadata) = vfs::metadata_async(source).await {
        let _ = vfs::set_readonly_async(destination, metadata.is_readonly()).await;
    }

    for entry in vfs::read_dir_async(source).await? {
        let child_source = entry.path().to_path_buf();
        let child_dest = destination.join(PathBuf::from(entry.file_name()));
        let child_meta = vfs::metadata_async(&child_source).await?;
        if child_meta.is_dir() {
            copy_directory_recursive(&child_source, &child_dest).await?;
        } else {
            copy_file_to_path(&child_source, &child_dest).await?;
        }
    }

    Ok(())
}

async fn copy_file_to_path(source: &Path, destination: &Path) -> io::Result<()> {
    ensure_parent_exists(destination).await?;

    vfs::copy_file(source, destination)?;

    if let Ok(metadata) = vfs::metadata_async(source).await {
        let _ = vfs::set_readonly_async(destination, metadata.is_readonly()).await;
    }

    Ok(())
}

async fn ensure_parent_exists(path: &Path) -> io::Result<()> {
    if let Some(parent) = path.parent() {
        if parent.as_os_str().is_empty() || parent == Path::new(".") {
            return Ok(());
        }
        if vfs::metadata_async(parent).await.is_err() {
            return Err(io::Error::new(
                io::ErrorKind::NotFound,
                format!("Destination parent \"{}\" does not exist", parent.display()),
            ));
        }
    }
    Ok(())
}

async fn same_physical_path(a: &Path, b: &Path) -> bool {
    if a == b {
        return true;
    }
    match (
        vfs::canonicalize_async(a).await,
        vfs::canonicalize_async(b).await,
    ) {
        (Ok(ca), Ok(cb)) => ca == cb,
        _ => false,
    }
}

async fn is_descendant(parent: &Path, candidate: &Path) -> bool {
    if candidate.starts_with(parent) && candidate != parent {
        return true;
    }
    match (
        vfs::canonicalize_async(parent).await,
        vfs::canonicalize_async(candidate).await,
    ) {
        (Ok(parent_canon), Ok(candidate_canon)) => {
            candidate_canon.starts_with(&parent_canon) && candidate_canon != parent_canon
        }
        _ => false,
    }
}

fn parse_force_flag(value: &Value) -> BuiltinResult<bool> {
    let text = extract_path(value, &COPYFILE_ERROR_FLAG_ARG)?;
    if text.eq_ignore_ascii_case("f") {
        Ok(true)
    } else {
        Err(copyfile_error_row(&COPYFILE_ERROR_FLAG_ARG))
    }
}

fn extract_path(value: &Value, error: &'static BuiltinErrorDescriptor) -> BuiltinResult<String> {
    match value {
        Value::String(text) => Ok(text.clone()),
        Value::CharArray(array) => {
            if array.rows == 1 {
                Ok(array.data.iter().collect())
            } else {
                Err(copyfile_error_row(error))
            }
        }
        Value::StringArray(array) => {
            if array.data.len() == 1 {
                Ok(array.data[0].clone())
            } else {
                Err(copyfile_error_row(error))
            }
        }
        _ => Err(copyfile_error_row(error)),
    }
}

fn message_identifier(error: &'static BuiltinErrorDescriptor) -> &'static str {
    error.identifier.unwrap_or("")
}

async fn gather_arguments(args: &[Value]) -> BuiltinResult<Vec<Value>> {
    let mut out = Vec::with_capacity(args.len());
    for value in args {
        out.push(
            gather_if_needed_async(value)
                .await
                .map_err(map_control_flow)?,
        );
    }
    Ok(out)
}

fn char_array_value(text: &str) -> Value {
    Value::CharArray(CharArray::new_row(text))
}

fn path_to_display(path: &Path) -> String {
    path.display().to_string()
}

#[cfg(test)]
pub(crate) mod tests {
    use super::super::REPL_FS_TEST_LOCK;
    use super::*;
    use std::fs::{self, File};
    use tempfile::tempdir;

    fn evaluate(args: &[Value]) -> BuiltinResult<CopyfileResult> {
        futures::executor::block_on(super::evaluate(args))
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_descriptor_signatures_cover_core_forms() {
        let labels: Vec<&str> = COPYFILE_DESCRIPTOR
            .signatures
            .iter()
            .map(|sig| sig.label)
            .collect();
        assert!(labels.contains(&"status = copyfile(source, destination)"));
        assert!(labels.contains(&"status = copyfile(source, destination, flag)"));
        assert!(labels.contains(&"[status, msg, msgID] = copyfile(source, destination)"));
        assert!(labels.contains(&"[status, msg, msgID] = copyfile(source, destination, flag)"));
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_copies_file_to_new_name() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("source.txt");
        let dest = temp.path().join("dest.txt");
        File::create(&source).expect("create source");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
        assert!(source.exists());
        assert!(dest.exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_copies_into_existing_directory() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("report.txt");
        let dest_dir = temp.path().join("reports");
        fs::create_dir(&dest_dir).expect("create dest dir");
        File::create(&source).expect("create source");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest_dir.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
        assert!(source.exists());
        assert!(dest_dir.join("report.txt").exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_force_overwrites_existing_file() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("draft.txt");
        let dest = temp.path().join("final.txt");
        File::create(&source).expect("create source");
        File::create(&dest).expect("create dest");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
            Value::from("f"),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
        assert!(source.exists());
        assert!(dest.exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_without_force_fails_when_destination_exists() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("draft.txt");
        let dest = temp.path().join("final.txt");
        File::create(&source).expect("create source");
        File::create(&dest).expect("create dest");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_DEST_EXISTS)
        );
        assert!(
            eval.message().contains("destination already exists"),
            "expected descriptive destination-exists message"
        );
        assert!(source.exists());
        assert!(dest.exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_copies_folder_tree() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source_dir = temp.path().join("data");
        let nested = source_dir.join("raw");
        fs::create_dir(&source_dir).expect("create source dir");
        fs::create_dir(&nested).expect("create nested dir");
        let file_path = nested.join("sample.txt");
        File::create(&file_path).expect("create sample");
        let dest_dir = temp.path().join("data_copy");

        let eval = evaluate(&[
            Value::from(source_dir.to_string_lossy().to_string()),
            Value::from(dest_dir.to_string_lossy().to_string()),
        ])
        .expect("copyfile");

        assert_eq!(eval.status(), 1.0);
        assert!(dest_dir.join("raw").exists());
        assert!(dest_dir.join("raw").join("sample.txt").exists());
        assert!(file_path.exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_pattern_requires_existing_directory() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let file = temp.path().join("file.log");
        File::create(&file).expect("create file");
        let pattern = temp.path().join("*.log");
        let dest = temp.path().join("missing");

        let eval = evaluate(&[
            Value::from(pattern.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_DEST_MISSING)
        );
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_pattern_copies_multiple_files() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let alpha = temp.path().join("alpha.log");
        let beta = temp.path().join("beta.log");
        File::create(&alpha).expect("create alpha");
        File::create(&beta).expect("create beta");
        let dest_dir = temp.path().join("logs");
        fs::create_dir(&dest_dir).expect("create dest dir");
        let pattern = temp.path().join("*.log");

        let eval = evaluate(&[
            Value::from(pattern.to_string_lossy().to_string()),
            Value::from(dest_dir.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
        assert!(dest_dir.join("alpha.log").exists());
        assert!(dest_dir.join("beta.log").exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_pattern_copies_all_matches() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let dest_dir = temp.path().join("logs");
        fs::create_dir(&dest_dir).expect("create dest dir");
        let file_a = temp.path().join("a.log");
        let file_b = temp.path().join("b.log");
        File::create(&file_a).expect("create a");
        File::create(&file_b).expect("create b");
        let pattern = temp.path().join("*.log");

        let eval = evaluate(&[
            Value::from(pattern.to_string_lossy().to_string()),
            Value::from(dest_dir.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
        assert!(dest_dir.join("a.log").exists());
        assert!(dest_dir.join("b.log").exists());
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_reports_missing_source() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("missing.txt");
        let dest = temp.path().join("dest.txt");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_SOURCE_NOT_FOUND)
        );
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_outputs_char_arrays() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("source.txt");
        let dest = temp.path().join("dest.txt");
        File::create(&source).expect("create source");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        let outputs = eval.outputs();
        assert_eq!(outputs.len(), 3);
        assert!(matches!(outputs[0], Value::Num(1.0)));
        assert!(matches!(outputs[1], Value::CharArray(ref ca) if ca.cols == 0));
        assert!(matches!(outputs[2], Value::CharArray(ref ca) if ca.cols == 0));
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_rejects_invalid_flag() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let err = evaluate(&[Value::from("a"), Value::from("b"), Value::Num(1.0)])
            .expect_err("expected error");
        assert_eq!(err.message(), COPYFILE_ERROR_FLAG_ARG.message);
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_force_flag_accepts_uppercase_char_array() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("draft.txt");
        let dest = temp.path().join("final.txt");
        File::create(&source).expect("create source");
        File::create(&dest).expect("create dest");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
            Value::CharArray(CharArray::new_row("F")),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_force_flag_accepts_uppercase_string() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("draft.txt");
        let dest = temp.path().join("final.txt");
        File::create(&source).expect("create source");
        File::create(&dest).expect("create dest");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(dest.to_string_lossy().to_string()),
            Value::from("F"),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 1.0);
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_same_path_fails() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let temp = tempdir().expect("temp dir");
        let source = temp.path().join("note.txt");
        File::create(&source).expect("create source");

        let eval = evaluate(&[
            Value::from(source.to_string_lossy().to_string()),
            Value::from(source.to_string_lossy().to_string()),
        ])
        .expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_SAME_PATH)
        );
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_reports_empty_source() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let eval = evaluate(&[Value::from(""), Value::from("dest.txt")]).expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_EMPTY_SOURCE)
        );
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_reports_empty_destination() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let eval = evaluate(&[Value::from("source.txt"), Value::from("")]).expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_EMPTY_DEST)
        );
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn copyfile_reports_invalid_pattern() {
        let _lock = REPL_FS_TEST_LOCK
            .lock()
            .unwrap_or_else(|poison| poison.into_inner());

        let eval = evaluate(&[Value::from("[*.txt"), Value::from("dest")]).expect("copyfile");
        assert_eq!(eval.status(), 0.0);
        assert_eq!(
            eval.message_id(),
            message_identifier(&COPYFILE_RESULT_PATTERN_ERROR)
        );
    }
}