nu-protocol 0.115.0

#![allow(unused_assignments)]
use crate::{Span, Type, ast::RedirectionSource, did_you_mean};
use miette::Diagnostic;
use serde::{Deserialize, Serialize};
use std::{
    fmt::Display,
    str::{Utf8Error, from_utf8},
};
use thiserror::Error;

#[derive(Clone, Debug, Error, Diagnostic, Serialize, Deserialize, PartialEq)]
pub enum ParseError {
    /// The parser encountered unexpected tokens, when the code should have
    /// finished. You should remove these or finish adding what you intended
    /// to add.
    #[error("Extra tokens in code.")]
    #[diagnostic(
        code(nu::parser::extra_tokens),
        help(
            "Remove the unexpected tokens, or check for a missing operator, delimiter, or newline above."
        )
    )]
    ExtraTokens(#[label = "extra tokens"] Span),

    #[error("Invalid characters after closing delimiter")]
    #[diagnostic(
        code(nu::parser::extra_token_after_closing_delimiter),
        help("Remove these characters, or check that a delimiter closed too early above.")
    )]
    ExtraTokensAfterClosingDelimiter(#[label = "invalid characters"] Span),

    #[error("Extra positional argument.")]
    #[diagnostic(code(nu::parser::extra_positional), help("Usage: {0}"))]
    ExtraPositional(String, #[label = "extra positional argument"] Span),

    #[error("Required positional parameter after optional parameter")]
    #[diagnostic(code(nu::parser::required_after_optional))]
    RequiredAfterOptional(
        String,
        #[label = "required parameter {0} after optional parameter"] Span,
    ),

    #[error("Unexpected end of code.")]
    #[diagnostic(code(nu::parser::unexpected_eof))]
    UnexpectedEof(String, #[label("expected closing {0}")] Span),

    /// A delimiter was opened but never closed.
    ///
    /// - `0`: expected closer (e.g. `"}"`, `"]"`, `")"`)
    /// - `1`: span of the **opening** delimiter
    /// - `2`: span where the closer was expected (primary — often mid-file or EOF)
    /// - `3`: help text (generic or heuristic structure hint)
    ///
    /// Primary label is the **expected closer** location so a deleted `}` near
    /// line N points the user at (or near) line N, not only at a distant opener.
    #[error("Unclosed delimiter.")]
    #[diagnostic(code(nu::parser::unclosed_delimiter), help("{3}"))]
    Unclosed(
        &'static str,
        #[label("unclosed — opens here (need `{0}`)")] Span,
        #[label(primary, "expected `{0}` here")] Span,
        String,
    ),

    /// A closer appeared without a matching opener (or mismatched kind).
    ///
    /// - `0` / `1`: open and close delimiter characters (e.g. `"{"`, `"}"`)
    /// - `2`: span of the unexpected closer (primary label)
    /// - `3`: help text
    #[error("Unbalanced delimiter.")]
    #[diagnostic(code(nu::parser::unbalanced_delimiter), help("{3}"))]
    Unbalanced(
        &'static str,
        &'static str,
        #[label("unexpected `{1}` (unbalanced with `{0}`)")] Span,
        String,
    ),

    #[error("Parse mismatch: expected {0}.")]
    #[diagnostic(
        code(nu::parser::parse_mismatch),
        help(
            "Check the syntax around this position — a typo, missing delimiter, or wrong separator is common."
        )
    )]
    Expected(&'static str, #[label("expected {0}")] Span),

    #[error("Parse mismatch: expected {0}.")]
    #[diagnostic(
        code(nu::parser::parse_mismatch_with_full_string_msg),
        help(
            "Check the syntax around this position — a typo, missing delimiter, or wrong separator is common."
        )
    )]
    ExpectedWithStringMsg(String, #[label("expected {0}")] Span),

    #[error("Parse mismatch: expected {0}.")]
    #[diagnostic(
        code(nu::parser::parse_mismatch_with_did_you_mean),
        help(
            "Check the syntax around this position — a typo, missing delimiter, or wrong separator is common."
        )
    )]
    ExpectedWithDidYouMean(&'static str, DidYouMean, #[label("expected {0}. {1}")] Span),

    #[error("Command does not support {0} input.")]
    #[diagnostic(code(nu::parser::input_type_mismatch))]
    InputMismatch(String, #[label("command doesn't support {0} input")] Span),

    #[error("Command output doesn't match {0}.")]
    #[diagnostic(code(nu::parser::output_type_mismatch))]
    OutputMismatch(
        Type,
        String,
        #[label("expected {0}, but command outputs {1}")] Span,
    ),

    #[error("Type mismatch during operation.")]
    #[diagnostic(code(nu::parser::type_mismatch))]
    Mismatch(String, String, #[label("expected {0}, found {1}")] Span), // expected, found, span

    #[error("The '&&' operator is not supported in Nushell")]
    #[diagnostic(
        code(nu::parser::shell_andand),
        help("use ';' instead of the shell '&&', or 'and' instead of the boolean '&&'")
    )]
    ShellAndAnd(#[label("instead of '&&', use ';' or 'and'")] Span),

    #[error("The '||' operator is not supported in Nushell")]
    #[diagnostic(
        code(nu::parser::shell_oror),
        help("use 'try' instead of the shell '||', or 'or' instead of the boolean '||'")
    )]
    ShellOrOr(#[label("instead of '||', use 'try' or 'or'")] Span),

    #[error("The '2>' shell operation is 'err>' in Nushell.")]
    #[diagnostic(code(nu::parser::shell_err))]
    ShellErrRedirect(#[label("use 'err>' instead of '2>' in Nushell")] Span),

    #[error("The '2>&1' shell operation is 'out+err>' in Nushell.")]
    #[diagnostic(
        code(nu::parser::shell_outerr),
        help("Nushell redirection will write all of stdout before stderr.")
    )]
    ShellOutErrRedirect(#[label("use 'out+err>' instead of '2>&1' in Nushell")] Span),

    #[error("Multiple redirections provided for {0}.")]
    #[diagnostic(code(nu::parser::multiple_redirections))]
    MultipleRedirections(
        RedirectionSource,
        #[label = "first redirection"] Span,
        #[label = "second redirection"] Span,
    ),

    #[error("Unexpected redirection.")]
    #[diagnostic(code(nu::parser::unexpected_redirection))]
    UnexpectedRedirection {
        #[label = "redirecting nothing"]
        span: Span,
    },

    /// One or more of the values have types not supported by the operator.
    #[error("The '{op}' operator does not work on values of type '{unsupported}'.")]
    #[diagnostic(code(nu::parser::operator_unsupported_type))]
    OperatorUnsupportedType {
        op: &'static str,
        unsupported: Type,
        #[label = "does not support '{unsupported}'"]
        op_span: Span,
        #[label("{unsupported}")]
        unsupported_span: Span,
        #[help]
        help: Option<&'static str>,
    },

    /// The operator supports the types of both values, but not the specific combination of their types.
    #[error("Types '{lhs}' and '{rhs}' are not compatible for the '{op}' operator.")]
    #[diagnostic(code(nu::parser::operator_incompatible_types))]
    OperatorIncompatibleTypes {
        op: &'static str,
        lhs: Type,
        rhs: Type,
        #[label = "does not operate between '{lhs}' and '{rhs}'"]
        op_span: Span,
        #[label("{lhs}")]
        lhs_span: Span,
        #[label("{rhs}")]
        rhs_span: Span,
        #[help]
        help: Option<&'static str>,
    },

    #[error("Capture of mutable variable.")]
    #[diagnostic(code(nu::parser::expected_keyword))]
    CaptureOfMutableVar(#[label("capture of mutable variable")] Span),

    #[error("Expected keyword.")]
    #[diagnostic(code(nu::parser::expected_keyword))]
    ExpectedKeyword(String, #[label("expected {0}")] Span),

    #[error("Unexpected keyword.")]
    #[diagnostic(
        code(nu::parser::unexpected_keyword),
        help("'{0}' keyword is allowed only in a module.")
    )]
    UnexpectedKeyword(String, #[label("unexpected {0}")] Span),

    #[error("Module `{0}` has a `main` command but `{0}` is a built-in parser keyword.")]
    #[diagnostic(
        code(nu::parser::keyword_shadow_module_main),
        help(
            "The `main` command cannot be invoked because `{0}` is intercepted by the parser. Either rename the module file, or remove `export def main` and use `use {0}.nu *` to import other commands."
        )
    )]
    KeywordShadowModuleMain(String, #[label("`{0}` is a parser keyword")] Span),

    #[error("Can't create alias to parser keyword.")]
    #[diagnostic(
        code(nu::parser::cant_alias_keyword),
        help("Only the following keywords can be aliased: {0}.")
    )]
    CantAliasKeyword(String, #[label("not supported in alias")] Span),

    #[error("Can't create alias to expression.")]
    #[diagnostic(
        code(nu::parser::cant_alias_expression),
        help("Only command calls can be aliased.")
    )]
    CantAliasExpression(String, #[label("aliasing {0} is not supported")] Span),

    #[error("Unknown operator")]
    #[diagnostic(code(nu::parser::unknown_operator), help("{1}"))]
    UnknownOperator(
        &'static str,
        &'static str,
        #[label("Operator '{0}' not supported")] Span,
    ),

    #[error("Statement used in pipeline.")]
    #[diagnostic(
        code(nu::parser::unexpected_keyword),
        help(
            "'{0}' keyword is not allowed in pipeline. Use '{0}' by itself, outside of a pipeline."
        )
    )]
    BuiltinCommandInPipeline(String, #[label("not allowed in pipeline")] Span),

    #[error("{0} statement used in pipeline.")]
    #[diagnostic(
        code(nu::parser::unexpected_keyword),
        help(
            "Assigning '{1}' to '{2}' does not produce a value to be piped. If the pipeline result is meant to be assigned to '{2}', use '{0} {2} = ({1} | ...)'."
        )
    )]
    AssignInPipeline(String, String, String, #[label("'{0}' in pipeline")] Span),

    #[error("`{0}` used as variable name.")]
    #[diagnostic(
        code(nu::parser::name_is_builtin_var),
        help(
            "'{0}' is the name of a builtin Nushell variable and cannot be used as a variable name"
        )
    )]
    NameIsBuiltinVar(String, #[label("already a builtin variable")] Span),

    #[error("Can't use parser keyword `{0}` as {1} name.")]
    #[diagnostic(
        code(nu::parser::name_is_keyword),
        help(
            "Parser keywords cannot be shadowed (including via module exports and `use *`). Choose a different {1} name so language constructs keep working."
        )
    )]
    NameIsKeyword(String, String, #[label("'{0}' is a parser keyword")] Span),

    #[error("Incorrect value")]
    #[diagnostic(code(nu::parser::incorrect_value), help("{2}"))]
    IncorrectValue(String, #[label("unexpected {0}")] Span, String),

    #[error("Invalid binary string.")]
    #[diagnostic(code(nu::parser::invalid_binary_string), help("{1}"))]
    InvalidBinaryString(#[label("invalid binary string")] Span, String),

    #[error("Multiple rest params.")]
    #[diagnostic(code(nu::parser::multiple_rest_params))]
    MultipleRestParams(#[label = "multiple rest params"] Span),

    #[error("Variable not found.")]
    #[diagnostic(code(nu::parser::variable_not_found))]
    VariableNotFound(DidYouMean, #[label = "variable not found. {0}"] Span),

    #[error("Use $env.{0} instead of ${0}.")]
    #[diagnostic(code(nu::parser::env_var_not_var))]
    EnvVarNotVar(String, #[label = "use $env.{0} instead of ${0}"] Span),

    #[error("Variable name not supported.")]
    #[diagnostic(code(nu::parser::variable_not_valid))]
    VariableNotValid(#[label = "variable name can't contain spaces or quotes"] Span),

    #[error("Alias name not supported.")]
    #[diagnostic(code(nu::parser::variable_not_valid))]
    AliasNotValid(
        #[label = "alias name can't be a number, a filesize, or contain #, ^, or %"] Span,
    ),

    #[error("Command name not supported.")]
    #[diagnostic(code(nu::parser::variable_not_valid))]
    CommandDefNotValid(
        #[label = "command name can't be a number, a filesize, or contain #, ^, or %"] Span,
    ),

    #[error("Module not found.")]
    #[diagnostic(
        code(nu::parser::module_not_found),
        help(
            "module files and their paths must be available before your script is run as parsing occurs before anything is evaluated"
        )
    )]
    ModuleNotFound(#[label = "module {1} not found"] Span, String),

    #[error("Missing mod.nu file.")]
    #[diagnostic(
        code(nu::parser::module_missing_mod_nu_file),
        help(
            "Directory {0} is missing a mod.nu file.\n\nWhen importing a directory as a Nushell module, it needs to contain a mod.nu file (can be empty). Alternatively, you can use .nu files in the directory as modules individually."
        )
    )]
    ModuleMissingModNuFile(
        String,
        #[label = "module directory is missing a mod.nu file"] Span,
    ),

    #[error("Circular import.")]
    #[diagnostic(code(nu::parser::circular_import), help("{0}"))]
    CircularImport(String, #[label = "detected circular import"] Span),

    #[error("Can't export {0} named same as the module.")]
    #[diagnostic(
        code(nu::parser::named_as_module),
        help(
            "Module {1} can't export {0} named the same as the module. Either change the module name, or export `{2}` {0}."
        )
    )]
    NamedAsModule(
        String,
        String,
        String,
        #[label = "can't export from module {1}"] Span,
    ),

    #[error("Module already contains 'main' command.")]
    #[diagnostic(
        code(nu::parser::module_double_main),
        help("Tried to add 'main' command to module '{0}' but it has already been added.")
    )]
    ModuleDoubleMain(
        String,
        #[label = "module '{0}' already contains 'main'"] Span,
    ),

    #[error("Can't export alias defined as 'main'.")]
    #[diagnostic(
        code(nu::parser::export_main_alias_not_allowed),
        help(
            "Exporting aliases as 'main' is not allowed. Either rename the alias or convert it to a custom command."
        )
    )]
    ExportMainAliasNotAllowed(#[label = "can't export from module"] Span),

    #[error("Active overlay not found.")]
    #[diagnostic(code(nu::parser::active_overlay_not_found))]
    ActiveOverlayNotFound(#[label = "not an active overlay"] Span),

    #[error("Overlay prefix mismatch.")]
    #[diagnostic(
        code(nu::parser::overlay_prefix_mismatch),
        help(
            "Overlay {0} already exists {1} a prefix. To add it again, do it {1} the --prefix flag."
        )
    )]
    OverlayPrefixMismatch(
        String,
        String,
        #[label = "already exists {1} a prefix"] Span,
    ),

    #[error("Module or overlay not found.")]
    #[diagnostic(
        code(nu::parser::module_or_overlay_not_found),
        help(
            "Requires either an existing overlay, a module, or an import pattern defining a module."
        )
    )]
    ModuleOrOverlayNotFound(#[label = "not a module or an overlay"] Span),

    #[error("Cannot remove the last overlay.")]
    #[diagnostic(
        code(nu::parser::cant_remove_last_overlay),
        help("At least one overlay must always be active.")
    )]
    CantRemoveLastOverlay(#[label = "this is the last overlay, can't remove it"] Span),

    #[error("Cannot hide default overlay.")]
    #[diagnostic(
        code(nu::parser::cant_hide_default_overlay),
        help("'{0}' is a default overlay. Default overlays cannot be hidden.")
    )]
    CantHideDefaultOverlay(String, #[label = "can't hide overlay"] Span),

    #[error("Cannot add overlay.")]
    #[diagnostic(code(nu::parser::cant_add_overlay_help), help("{0}"))]
    CantAddOverlayHelp(String, #[label = "cannot add this overlay"] Span),

    #[error("Duplicate command definition within a block.")]
    #[diagnostic(code(nu::parser::duplicate_command_def))]
    DuplicateCommandDef(#[label = "defined more than once"] Span),

    #[error("Unknown command.")]
    #[diagnostic(
        code(nu::parser::unknown_command),
        // TODO: actual suggestions like "Did you mean `foo`?"
    )]
    UnknownCommand(#[label = "unknown command"] Span),

    #[error("Non-UTF8 string.")]
    #[diagnostic(code(nu::parser::non_utf8))]
    NonUtf8(#[label = "non-UTF8 string"] Span),

    #[error("The `{0}` command doesn't have flag `{1}`.")]
    #[diagnostic(code(nu::parser::unknown_flag), help("{3}"))]
    UnknownFlag(String, String, #[label = "unknown flag"] Span, String),

    #[error("Unknown type.")]
    #[diagnostic(code(nu::parser::unknown_type))]
    UnknownType(#[label = "unknown type"] Span),

    #[error("Missing flag argument.")]
    #[diagnostic(code(nu::parser::missing_flag_param))]
    MissingFlagParam(String, #[label = "flag missing {0} argument"] Span),

    #[error("Only the last flag in a short flag batch can take an argument.")]
    #[diagnostic(code(nu::parser::only_last_flag_in_batch_can_take_arg))]
    OnlyLastFlagInBatchCanTakeArg(#[label = "only the last flag can take args"] Span),

    #[error("Missing required positional argument.")]
    #[diagnostic(
        code(nu::parser::missing_positional),
        help("Usage: {2}. Use `--help` for more information.")
    )]
    MissingPositional(String, #[label("missing {0}")] Span, String),

    #[error("Missing argument to `{1}`.")]
    #[diagnostic(code(nu::parser::keyword_missing_arg))]
    KeywordMissingArgument(
        String,
        String,
        #[label("missing {0} value that follows {1}")] Span,
    ),

    #[error("Missing type.")]
    #[diagnostic(code(nu::parser::missing_type))]
    MissingType(#[label = "expected type"] Span),

    #[error("Type mismatch.")]
    #[diagnostic(code(nu::parser::type_mismatch))]
    TypeMismatch(Type, Type, #[label("expected {0}, found {1}")] Span), // expected, found, span

    #[error("Type mismatch.")]
    #[diagnostic(code(nu::parser::type_mismatch_help), help("{3}"))]
    TypeMismatchHelp(Type, Type, #[label("expected {0}, found {1}")] Span, String), // expected, found, span, help

    #[error("Missing required flag.")]
    #[diagnostic(code(nu::parser::missing_required_flag))]
    MissingRequiredFlag(String, #[label("missing required flag {0}")] Span),

    #[error("Incomplete math expression.")]
    #[diagnostic(code(nu::parser::incomplete_math_expression))]
    IncompleteMathExpression(#[label = "incomplete math expression"] Span),

    #[error("Unknown state.")]
    #[diagnostic(code(nu::parser::unknown_state))]
    UnknownState(String, #[label("{0}")] Span),

    #[error("Internal error.")]
    #[diagnostic(code(nu::parser::unknown_state))]
    InternalError(String, #[label("{0}")] Span),

    #[error("Parser incomplete.")]
    #[diagnostic(code(nu::parser::parser_incomplete))]
    IncompleteParser(#[label = "parser support missing for this expression"] Span),

    #[error("Rest parameter needs a name.")]
    #[diagnostic(code(nu::parser::rest_needs_name))]
    RestNeedsName(#[label = "needs a parameter name"] Span),

    #[error("Parameter not correct type.")]
    #[diagnostic(code(nu::parser::parameter_mismatch_type))]
    ParameterMismatchType(
        String,
        String,
        String,
        #[label = "parameter {0} needs to be '{1}' instead of '{2}'"] Span,
    ),

    #[error("Default values should be constant expressions.")]
    #[diagnostic(code(nu::parser::non_constant_default_value))]
    NonConstantDefaultValue(#[label = "expected a constant value"] Span),

    #[error("Extra columns.")]
    #[diagnostic(code(nu::parser::extra_columns))]
    ExtraColumns(
        usize,
        #[label("expected {0} column{}", if *.0 == 1 { "" } else { "s" })] Span,
    ),

    #[error("Missing columns.")]
    #[diagnostic(code(nu::parser::missing_columns))]
    MissingColumns(
        usize,
        #[label("expected {0} column{}", if *.0 == 1 { "" } else { "s" })] Span,
    ),

    #[error("{0}")]
    #[diagnostic(code(nu::parser::assignment_mismatch))]
    AssignmentMismatch(String, String, #[label("{1}")] Span),

    #[error("Wrong import pattern structure.")]
    #[diagnostic(code(nu::parser::wrong_import_pattern))]
    WrongImportPattern(String, #[label = "{0}"] Span),

    #[error("Export not found.")]
    #[diagnostic(code(nu::parser::export_not_found))]
    ExportNotFound(#[label = "could not find imports"] Span),

    #[error("File not found")]
    #[diagnostic(
        code(nu::parser::sourced_file_not_found),
        help("sourced files need to be available before your script is run")
    )]
    SourcedFileNotFound(String, #[label("File not found: {0}")] Span),

    #[error("Script file is too large to load with `run`")]
    #[diagnostic(
        code(nu::parser::script_file_too_large),
        help(
            "The `run` command refuses files larger than {max_size} bytes at parse time (file is {size} bytes). Use a smaller script, or invoke large scripts with `nu path/to/script.nu`."
        )
    )]
    ScriptFileTooLarge {
        path: String,
        size: u64,
        max_size: u64,
        #[label("file too large for `run`: {path}")]
        span: Span,
    },

    #[error("Script file does not appear to be text")]
    #[diagnostic(
        code(nu::parser::script_file_not_text),
        help(
            "The `run` command only loads UTF-8 text scripts. Binary data (NUL bytes, invalid UTF-8, or dense control characters) is rejected."
        )
    )]
    ScriptFileNotText {
        path: String,
        #[label("not a text script for `run`: {path}")]
        span: Span,
    },

    #[error("File not found")]
    #[diagnostic(
        code(nu::parser::registered_file_not_found),
        help("registered files need to be available before your script is run")
    )]
    RegisteredFileNotFound(String, #[label("File not found: {0}")] Span),

    #[error("File not found")]
    #[diagnostic(code(nu::parser::file_not_found))]
    FileNotFound(String, #[label("File not found: {0}")] Span),

    #[error("Plugin not found")]
    #[diagnostic(
        code(nu::parser::plugin_not_found),
        help(
            "plugins need to be added to the plugin registry file before your script is run (see `plugin add`)"
        )
    )]
    PluginNotFound {
        name: String,
        #[label("Plugin not found: {name}")]
        name_span: Span,
        #[label("in this registry file")]
        plugin_config_span: Option<Span>,
    },

    #[error("Invalid literal")] // <problem> in <entity>.
    #[diagnostic()]
    InvalidLiteral(String, String, #[label("{0} in {1}")] Span),

    #[error("{0}")]
    #[diagnostic()]
    LabeledError(String, String, #[label("{1}")] Span),

    #[error("{error}")]
    #[diagnostic(help("{help}"))]
    LabeledErrorWithHelp {
        error: String,
        label: String,
        help: String,
        #[label("{label}")]
        span: Span,
    },

    #[error("Redirection can not be used with {0}.")]
    #[diagnostic()]
    RedirectingBuiltinCommand(
        &'static str,
        #[label("not allowed here")] Span,
        #[label("...and here")] Option<Span>,
    ),

    #[error("This command does not have a ...rest parameter")]
    #[diagnostic(
        code(nu::parser::unexpected_spread_arg),
        help(
            "To spread arguments, the command needs to define a multi-positional parameter in its signature, such as ...rest"
        )
    )]
    UnexpectedSpreadArg(String, #[label = "unexpected spread argument"] Span),

    /// Invalid assignment left-hand side
    ///
    /// ## Resolution
    ///
    /// Assignment requires that you assign to a mutable variable or cell path.
    #[error("Assignment to an immutable variable.")]
    #[diagnostic(
        code(nu::parser::assignment_requires_mutable_variable),
        help("declare the variable with `mut`, or shadow it again with `let`")
    )]
    AssignmentRequiresMutableVar(#[label("needs to be a mutable variable")] Span),

    /// Invalid assignment left-hand side
    ///
    /// ## Resolution
    ///
    /// Assignment requires that you assign to a variable or variable cell path.
    #[error("Assignment operations require a variable.")]
    #[diagnostic(
        code(nu::parser::assignment_requires_variable),
        help("try assigning to a variable or a cell path of a variable")
    )]
    AssignmentRequiresVar(#[label("needs to be a variable")] Span),

    #[error("Attributes must be followed by a definition.")]
    #[diagnostic(
        code(nu::parser::attribute_requires_definition),
        help("try following this line with a `def` or `extern` definition")
    )]
    AttributeRequiresDefinition(#[label("must be followed by a definition")] Span),
}

impl ParseError {
    /// Span covering the first `len` bytes of `span` (clamped to `span.end`).
    ///
    /// Used when labeling a multi-byte construct's opening delimiter.
    pub fn opener_span(span: Span, len: usize) -> Span {
        Span::new(span.start, span.start.saturating_add(len).min(span.end))
    }

    /// Build an [`Unclosed`](ParseError::Unclosed) with default help text.
    pub fn unclosed(delimiter: &'static str, open_span: Span, end_span: Span) -> Self {
        Self::Unclosed(
            delimiter,
            open_span,
            end_span,
            default_unclosed_help(delimiter, None),
        )
    }

    /// Build an [`Unclosed`](ParseError::Unclosed) with an optional structure hint
    /// (e.g. `record field ls`, `def foo`). Empty/`None` uses generic help.
    pub fn unclosed_with_hint(
        delimiter: &'static str,
        open_span: Span,
        end_span: Span,
        structure_hint: Option<&str>,
    ) -> Self {
        Self::Unclosed(
            delimiter,
            open_span,
            end_span,
            default_unclosed_help(delimiter, structure_hint),
        )
    }

    /// Build an [`Unbalanced`](ParseError::Unbalanced) with default help text.
    pub fn unbalanced(open: &'static str, close: &'static str, close_span: Span) -> Self {
        Self::Unbalanced(
            open,
            close,
            close_span,
            default_unbalanced_help(open, close),
        )
    }

    pub fn span(&self) -> Span {
        match self {
            ParseError::ExtraTokens(s) => *s,
            ParseError::ExtraPositional(_, s) => *s,
            ParseError::UnexpectedEof(_, s) => *s,
            // Jump-to-error: prefer where the closer was expected (mid-file or EOF).
            ParseError::Unclosed(_, _open, end, _) => *end,
            ParseError::Unbalanced(_, _, close, _) => *close,
            ParseError::Expected(_, s) => *s,
            ParseError::ExpectedWithStringMsg(_, s) => *s,
            ParseError::ExpectedWithDidYouMean(_, _, s) => *s,
            ParseError::Mismatch(_, _, s) => *s,
            ParseError::OperatorUnsupportedType { op_span, .. } => *op_span,
            ParseError::OperatorIncompatibleTypes { op_span, .. } => *op_span,
            ParseError::ExpectedKeyword(_, s) => *s,
            ParseError::UnexpectedKeyword(_, s) => *s,
            ParseError::CantAliasKeyword(_, s) => *s,
            ParseError::CantAliasExpression(_, s) => *s,
            ParseError::BuiltinCommandInPipeline(_, s) => *s,
            ParseError::AssignInPipeline(_, _, _, s) => *s,
            ParseError::NameIsBuiltinVar(_, s) => *s,
            ParseError::NameIsKeyword(_, _, s) => *s,
            ParseError::CaptureOfMutableVar(s) => *s,
            ParseError::IncorrectValue(_, s, _) => *s,
            ParseError::InvalidBinaryString(s, _) => *s,
            ParseError::MultipleRestParams(s) => *s,
            ParseError::VariableNotFound(_, s) => *s,
            ParseError::EnvVarNotVar(_, s) => *s,
            ParseError::VariableNotValid(s) => *s,
            ParseError::AliasNotValid(s) => *s,
            ParseError::CommandDefNotValid(s) => *s,
            ParseError::ModuleNotFound(s, _) => *s,
            ParseError::ModuleMissingModNuFile(_, s) => *s,
            ParseError::NamedAsModule(_, _, _, s) => *s,
            ParseError::ModuleDoubleMain(_, s) => *s,
            ParseError::ExportMainAliasNotAllowed(s) => *s,
            ParseError::CircularImport(_, s) => *s,
            ParseError::ModuleOrOverlayNotFound(s) => *s,
            ParseError::ActiveOverlayNotFound(s) => *s,
            ParseError::OverlayPrefixMismatch(_, _, s) => *s,
            ParseError::CantRemoveLastOverlay(s) => *s,
            ParseError::CantHideDefaultOverlay(_, s) => *s,
            ParseError::CantAddOverlayHelp(_, s) => *s,
            ParseError::DuplicateCommandDef(s) => *s,
            ParseError::UnknownCommand(s) => *s,
            ParseError::NonUtf8(s) => *s,
            ParseError::UnknownFlag(_, _, s, _) => *s,
            ParseError::RequiredAfterOptional(_, s) => *s,
            ParseError::UnknownType(s) => *s,
            ParseError::MissingFlagParam(_, s) => *s,
            ParseError::OnlyLastFlagInBatchCanTakeArg(s) => *s,
            ParseError::MissingPositional(_, s, _) => *s,
            ParseError::KeywordMissingArgument(_, _, s) => *s,
            ParseError::MissingType(s) => *s,
            ParseError::TypeMismatch(_, _, s) => *s,
            ParseError::TypeMismatchHelp(_, _, s, _) => *s,
            ParseError::InputMismatch(_, s) => *s,
            ParseError::OutputMismatch(_, _, s) => *s,
            ParseError::MissingRequiredFlag(_, s) => *s,
            ParseError::IncompleteMathExpression(s) => *s,
            ParseError::UnknownState(_, s) => *s,
            ParseError::InternalError(_, s) => *s,
            ParseError::IncompleteParser(s) => *s,
            ParseError::RestNeedsName(s) => *s,
            ParseError::ParameterMismatchType(_, _, _, s) => *s,
            ParseError::NonConstantDefaultValue(s) => *s,
            ParseError::ExtraColumns(_, s) => *s,
            ParseError::MissingColumns(_, s) => *s,
            ParseError::AssignmentMismatch(_, _, s) => *s,
            ParseError::WrongImportPattern(_, s) => *s,
            ParseError::ExportNotFound(s) => *s,
            ParseError::SourcedFileNotFound(_, s) => *s,
            ParseError::ScriptFileTooLarge { span, .. } => *span,
            ParseError::ScriptFileNotText { span, .. } => *span,
            ParseError::RegisteredFileNotFound(_, s) => *s,
            ParseError::FileNotFound(_, s) => *s,
            ParseError::PluginNotFound { name_span, .. } => *name_span,
            ParseError::LabeledError(_, _, s) => *s,
            ParseError::ShellAndAnd(s) => *s,
            ParseError::ShellOrOr(s) => *s,
            ParseError::ShellErrRedirect(s) => *s,
            ParseError::ShellOutErrRedirect(s) => *s,
            ParseError::MultipleRedirections(_, _, s) => *s,
            ParseError::UnexpectedRedirection { span } => *span,
            ParseError::UnknownOperator(_, _, s) => *s,
            ParseError::InvalidLiteral(_, _, s) => *s,
            ParseError::LabeledErrorWithHelp { span: s, .. } => *s,
            ParseError::RedirectingBuiltinCommand(_, s, _) => *s,
            ParseError::UnexpectedSpreadArg(_, s) => *s,
            ParseError::ExtraTokensAfterClosingDelimiter(s) => *s,
            ParseError::AssignmentRequiresVar(s) => *s,
            ParseError::AssignmentRequiresMutableVar(s) => *s,
            ParseError::AttributeRequiresDefinition(s) => *s,
            ParseError::KeywordShadowModuleMain(_, s) => *s,
        }
    }
}

fn default_unclosed_help(delimiter: &str, structure_hint: Option<&str>) -> String {
    match structure_hint {
        Some(hint) if !hint.is_empty() => format!(
            "Add a matching `{delimiter}` to close {hint}, or check that an earlier closer closed the wrong block."
        ),
        _ => format!(
            "Add a matching `{delimiter}` to close this delimiter, or check that an earlier closer closed the wrong block."
        ),
    }
}

fn default_unbalanced_help(open: &str, close: &str) -> String {
    format!(
        "Remove this `{close}` if it is extra, or add a matching `{open}` earlier. If you closed a block too early, the real mistake may be above."
    )
}

#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
pub struct DidYouMean(Option<String>);

fn did_you_mean_impl(possibilities_bytes: &[&[u8]], input_bytes: &[u8]) -> Option<String> {
    let input = from_utf8(input_bytes).ok()?;
    let possibilities = possibilities_bytes
        .iter()
        .map(|p| from_utf8(p))
        .collect::<Result<Vec<&str>, Utf8Error>>()
        .ok()?;
    did_you_mean(&possibilities, input)
}
impl DidYouMean {
    pub fn new(possibilities_bytes: &[&[u8]], input_bytes: &[u8]) -> DidYouMean {
        DidYouMean(did_you_mean_impl(possibilities_bytes, input_bytes))
    }
}

impl From<Option<String>> for DidYouMean {
    fn from(value: Option<String>) -> Self {
        Self(value)
    }
}

impl Display for DidYouMean {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        if let Some(suggestion) = &self.0 {
            write!(f, "Did you mean '{suggestion}'?")
        } else {
            write!(f, "")
        }
    }
}