use std::sync::Arc;
use serde_json::{json, Value};
use crate::tools::base::{ToolContext, ToolSpec};
use crate::tools::common::{
coerce_truthy_arg, parse_integer_arg, path_escapes_workspace_error, stringify_tool_arg,
tool_error,
};
use crate::types::{ToolArguments, ToolExecutionResult};
use super::super::workspace_backend_error;
use super::{READ_FILE_MAX_CHARS, READ_FILE_MAX_LINES};
pub fn read_file(context: &mut ToolContext, arguments: &ToolArguments) -> ToolExecutionResult {
let spec = read_file_tool();
(spec.handler)(context, arguments)
}
pub(crate) fn read_file_tool() -> ToolSpec {
let mut spec = ToolSpec::new(
"read_file",
"Read a text file from the current workspace.",
Arc::new(|context, arguments| {
if !arguments.contains_key("path") {
return tool_error("missing required argument: path");
}
let path = stringify_tool_arg(arguments.get("path"), "");
if let Err(error) = context.resolve_workspace_path(&path) {
return path_escapes_workspace_error(error);
}
let backend = context.effective_workspace_backend();
match backend.file_info(&path) {
Ok(Some(info)) if info.is_file => {}
Ok(_) => return tool_error(format!("file not found: {path}")),
Err(error) => return workspace_backend_error(error),
}
let start_line = match arguments.get("start_line") {
Some(value) => match parse_integer_arg(value) {
Ok(line) => line.max(1) as usize,
Err(_) => return tool_error("`start_line`/`end_line` must be integers"),
},
None => 1,
};
let end_line = match arguments.get("end_line") {
Some(value) => match parse_integer_arg(value) {
Ok(line) => Some(line.max(start_line as i64) as usize),
Err(_) => return tool_error("`start_line`/`end_line` must be integers"),
},
None => None,
};
let show_line_numbers = coerce_truthy_arg(arguments.get("show_line_numbers"), false);
match backend.read_text(&path) {
Ok(text) => read_text_result(&path, &text, start_line, end_line, show_line_numbers),
Err(error) => workspace_backend_error(error),
}
}),
);
if let Some(schema) = crate::tools::schemas::schema_for("read_file") {
spec.schema = schema;
}
spec
}
fn read_text_result(
path: &str,
text: &str,
start_line: usize,
end_line: Option<usize>,
show_line_numbers: bool,
) -> ToolExecutionResult {
let lines = text.lines().collect::<Vec<_>>();
let requested_start_index = start_line.saturating_sub(1);
let slice_start_index = requested_start_index.min(lines.len());
let slice_end_index = end_line
.unwrap_or(lines.len())
.min(lines.len())
.max(slice_start_index);
let selected = &lines[slice_start_index..slice_end_index];
let selected_line_count = selected.len();
let actual_start_line = requested_start_index + 1;
let actual_end_line = requested_start_index + selected_line_count;
let content = selected
.iter()
.enumerate()
.map(|(offset, line)| {
if show_line_numbers {
format!("{}: {line}", actual_start_line + offset)
} else {
(*line).to_string()
}
})
.collect::<Vec<_>>()
.join("\n");
if selected_line_count > READ_FILE_MAX_LINES || content.len() > READ_FILE_MAX_CHARS {
return oversized_read_result(
path,
text,
ReadSelection {
start_line,
actual_start_line,
actual_end_line,
selected_line_count,
selected_char_count: content.len(),
show_line_numbers,
},
);
}
ToolExecutionResult::success(
"",
json!({
"path": path,
"start_line": actual_start_line,
"end_line": actual_end_line,
"show_line_numbers": show_line_numbers,
"content": content,
})
.to_string(),
)
}
struct ReadSelection {
start_line: usize,
actual_start_line: usize,
actual_end_line: usize,
selected_line_count: usize,
selected_char_count: usize,
show_line_numbers: bool,
}
fn oversized_read_result(path: &str, text: &str, selection: ReadSelection) -> ToolExecutionResult {
let total_lines = text.lines().count();
let total_chars = text.len();
let suggested_start = selection.start_line.min(total_lines.max(1));
let suggested_end = (suggested_start + READ_FILE_MAX_LINES - 1).min(total_lines);
ToolExecutionResult::success(
"",
json!({
"path": path,
"start_line": selection.actual_start_line,
"end_line": selection.actual_end_line,
"show_line_numbers": selection.show_line_numbers,
"content": Value::Null,
"file_info": {
"total_lines": total_lines,
"total_chars": total_chars,
},
"requested": {
"line_count": selection.selected_line_count,
"char_count": selection.selected_char_count,
},
"limits": {
"max_lines": READ_FILE_MAX_LINES,
"max_chars": READ_FILE_MAX_CHARS,
},
"suggested_range": {
"start_line": suggested_start,
"end_line": suggested_end,
},
"message": "Requested read exceeds limits. Use start_line/end_line for a smaller range.",
})
.to_string(),
)
}