source-map-cache 0.1.0

/*
 * Copyright (c) Peter Bjorklund. All rights reserved. https://github.com/swamp/swamp
 * Licensed under the MIT License. See LICENSE in the project root for license information.
 */
use pathdiff::diff_paths;
use seq_map::SeqMap;
use source_map_node::{Node, Span};
use std::fmt::Debug;
use std::io::ErrorKind;
use std::path::{Path, PathBuf};
use std::{fs, io};
pub mod prelude;
pub type FileId = u16;

pub struct KeepTrackOfSourceLine {
    pub last_line_info: SourceFileLineInfo,
    pub current_line: usize,
}

impl Default for KeepTrackOfSourceLine {
    fn default() -> Self {
        Self::new()
    }
}

impl KeepTrackOfSourceLine {
    #[must_use]
    pub const fn new() -> Self {
        Self {
            last_line_info: SourceFileLineInfo {
                row: usize::MAX,
                file_id: usize::MAX,
            },
            current_line: usize::MAX,
        }
    }

    pub fn check_if_new_line(&mut self, found: &SourceFileLineInfo) -> Option<(usize, usize)> {
        if self.last_line_info.file_id != found.file_id || found.row != self.current_line {
            self.last_line_info = found.clone();
            self.current_line = self.last_line_info.row;
            Some((self.last_line_info.row, self.last_line_info.row))
        } else if found.row == self.current_line {
            None
        } else {
            let line_start = self.current_line;
            self.current_line = found.row;
            Some((line_start, found.row))
        }
    }
}

#[derive(Eq, PartialEq, Clone)]
pub struct SourceFileLineInfo {
    pub row: usize,
    pub file_id: usize,
}

#[derive(Debug)]
pub struct FileInfo {
    pub mount_name: String,
    pub relative_path: PathBuf,
    pub contents: String,
    pub line_offsets: Box<[u16]>,
}

#[derive(Debug)]
pub struct SourceMap {
    pub mounts: SeqMap<String, PathBuf>,
    pub cache: SeqMap<FileId, FileInfo>,
    pub file_cache: SeqMap<(String, String), FileId>,
    pub next_file_id: FileId,
}

#[derive(Debug)]
pub struct RelativePath(pub String);

impl SourceMap {
    /// # Errors
    ///
    pub fn new(mounts: &SeqMap<String, PathBuf>) -> io::Result<Self> {
        let mut canonical_mounts = SeqMap::new();
        for (mount_name, base_path) in mounts {
            let canon_path = base_path.canonicalize().map_err(|_| {
                io::Error::new(
                    io::ErrorKind::InvalidData,
                    format!("could not canonicalize {base_path:?}"),
                )
            })?;

            if !canon_path.is_dir() {
                return Err(io::Error::new(
                    ErrorKind::NotFound,
                    format!("{canon_path:?} is not a directory"),
                ));
            }
            canonical_mounts
                .insert(mount_name.clone(), canon_path)
                .map_err(|_| {
                    io::Error::new(io::ErrorKind::InvalidData, "could not insert mount")
                })?;
        }
        Ok(Self {
            mounts: canonical_mounts,
            cache: SeqMap::new(),
            file_cache: SeqMap::new(),
            next_file_id: 1,
        })
    }

    /// # Errors
    ///
    pub fn add_mount(&mut self, name: &str, path: &Path) -> io::Result<()> {
        if !path.is_dir() {
            return Err(io::Error::new(
                ErrorKind::NotFound,
                format!("{path:?} is not a directory"),
            ));
        }
        self.mounts
            .insert(name.to_string(), path.to_path_buf())
            .map_err(|_| io::Error::new(io::ErrorKind::InvalidData, "could not insert mount"))
    }

    #[must_use]
    pub fn base_path(&self, name: &str) -> &Path {
        self.mounts.get(&name.to_string()).unwrap_or_else(|| {
            panic!("could not find path {name}");
        })
    }

    pub fn read_file(&mut self, path: &Path, mount_name: &str) -> io::Result<(FileId, String)> {
        let found_base_path = self.base_path(mount_name);
        let relative_path = diff_paths(path, found_base_path)
            .unwrap_or_else(|| panic!("could not find relative path {path:?} {found_base_path:?}"));

        let contents = fs::read_to_string(path)?;

        let id = self.next_file_id;
        self.next_file_id += 1;

        self.add_manual(id, mount_name, &relative_path, &contents);

        Ok((id, contents))
    }

    pub fn add_to_cache(
        &mut self,
        mount_name: &str,
        relative_path: &Path,
        contents: &str,
        file_id: FileId,
    ) {
        self.add_manual(file_id, mount_name, relative_path, contents);
    }

    pub fn add_manual(
        &mut self,
        id: FileId,
        mount_name: &str,
        relative_path: &Path,
        contents: &str,
    ) {
        let line_offsets = Self::compute_line_offsets(contents);

        self.cache
            .insert(
                id,
                FileInfo {
                    mount_name: mount_name.to_string(),
                    relative_path: relative_path.to_path_buf(),
                    contents: contents.to_string(),
                    line_offsets,
                },
            )
            .expect("could not add file info");

        // Update file_cache to maintain consistency
        self.file_cache
            .insert(
                (
                    mount_name.to_string(),
                    relative_path.to_str().unwrap().to_string(),
                ),
                id,
            )
            .expect("could not add to file cache");
    }

    pub fn add_manual_no_id(
        &mut self,
        mount_name: &str,
        relative_path: &Path,
        contents: &str,
    ) -> FileId {
        let line_offsets = Self::compute_line_offsets(contents);
        let id = self.next_file_id;
        self.next_file_id += 1;

        self.cache
            .insert(
                id,
                FileInfo {
                    mount_name: mount_name.to_string(),
                    relative_path: relative_path.to_path_buf(),
                    contents: contents.to_string(),
                    line_offsets,
                },
            )
            .expect("could not add file info");

        // Update file_cache to maintain consistency
        self.file_cache
            .insert(
                (
                    mount_name.to_string(),
                    relative_path.to_str().unwrap().to_string(),
                ),
                id,
            )
            .expect("could not add to file cache");

        id
    }

    pub fn read_file_relative(
        &mut self,
        mount_name: &str,
        relative_path: &str,
    ) -> io::Result<(FileId, String)> {
        if let Some(found_in_cache) = self
            .file_cache
            .get(&(mount_name.to_string(), relative_path.to_string()))
        {
            let contents = self.cache.get(found_in_cache).unwrap().contents.clone();
            return Ok((*found_in_cache, contents));
        }

        let buf = self.to_file_system_path(mount_name, relative_path)?;
        self.read_file(&buf, mount_name)
    }

    fn to_file_system_path(&self, mount_name: &str, relative_path: &str) -> io::Result<PathBuf> {
        let base_path = self.base_path(mount_name).to_path_buf();
        let mut path_buf = base_path;

        path_buf.push(relative_path);

        path_buf.canonicalize().map_err(|_| {
            io::Error::other(format!(
                "path is wrong mount:{mount_name} relative:{relative_path}",
            ))
        })
    }

    fn compute_line_offsets(contents: &str) -> Box<[u16]> {
        let mut offsets = Vec::new();
        offsets.push(0);

        // Track positions of all newlines
        for (i, &byte) in contents.as_bytes().iter().enumerate() {
            if byte == b'\n' {
                // Safety: new line is always encoded as single octet
                let next_line_start = u16::try_from(i + 1).expect("too big file");
                offsets.push(next_line_start);
            }
        }

        // Always add the end of file position if it's not already there
        // (happens when file doesn't end with newline)
        let eof_offset = u16::try_from(contents.len()).expect("too big file");
        if offsets.last().is_none_or(|&last| last != eof_offset) {
            offsets.push(eof_offset);
        }

        offsets.into_boxed_slice()
    }

    #[must_use]
    pub fn get_span_source(&self, file_id: FileId, offset: usize, length: usize) -> Option<&str> {
        let file_info = self.cache.get(&file_id)?;

        let start = offset;
        let end = offset + length;

        // Verify both start and end are on character boundaries
        if start > file_info.contents.len()
            || end > file_info.contents.len()
            || !file_info.contents.is_char_boundary(start)
            || !file_info.contents.is_char_boundary(end)
        {
            // Invalid offsets - not on character boundaries
            return None;
        }

        Some(&file_info.contents[start..end])
    }

    #[must_use]
    pub fn get_source_line(&self, file_id: FileId, line_number: usize) -> Option<&str> {
        let file_info = self.cache.get(&file_id)?;

        // Check if the requested line number is valid
        if line_number == 0 || line_number >= file_info.line_offsets.len() {
            return None;
        }

        let start_offset = file_info.line_offsets[line_number - 1] as usize;
        let end_offset = file_info.line_offsets[line_number] as usize;

        let line = &file_info.contents[start_offset..end_offset];

        // Remove trailing newline if present.
        // Some files may not end with a newline.
        Some(line.strip_suffix('\n').unwrap_or(line))
    }

    #[must_use]
    pub fn get_span_location_utf8(&self, file_id: FileId, offset: usize) -> Option<(usize, usize)> {
        let file_info = self.cache.get(&file_id)?;
        let offset = offset as u16;

        let octet_offset = offset as usize;

        // Verify offset is on a character boundary
        if octet_offset > file_info.contents.len()
            || !file_info.contents.is_char_boundary(octet_offset)
        {
            // Invalid offset - not on a character boundary
            return None;
        }

        // Find the line containing 'offset' via binary search.
        let line_idx = file_info
            .line_offsets
            .binary_search(&offset)
            .unwrap_or_else(|insert_point| insert_point.saturating_sub(1));

        // Determine the start of the line in bytes
        let line_start = file_info.line_offsets[line_idx] as usize;

        // Extract the line slice from line_start to offset
        let line_text = &file_info.contents[line_start..octet_offset];

        // Count UTF-8 characters in that range, because that is what the end user sees in their editor.
        let column_character_offset = line_text.chars().count();

        // Add one so it makes more sense to the end user
        Some((line_idx + 1, column_character_offset + 1))
    }

    #[must_use]
    pub fn fetch_relative_filename(&self, file_id: FileId) -> &str {
        self.cache
            .get(&file_id)
            .unwrap()
            .relative_path
            .to_str()
            .unwrap()
    }

    pub fn minimal_relative_path(target: &Path, current_dir: &Path) -> io::Result<PathBuf> {
        let current_dir_components = current_dir.components().collect::<Vec<_>>();
        let target_components = target.components().collect::<Vec<_>>();

        let mut common_prefix_len = 0;
        for i in 0..std::cmp::min(current_dir_components.len(), target_components.len()) {
            if current_dir_components[i] == target_components[i] {
                common_prefix_len += 1;
            } else {
                break;
            }
        }

        let mut relative_path = PathBuf::new();

        for _ in 0..(current_dir_components.len() - common_prefix_len) {
            relative_path.push("..");
        }

        for component in &target_components[common_prefix_len..] {
            relative_path.push(component);
        }
        Ok(relative_path)
    }

    pub fn get_relative_path_to(&self, file_id: FileId, current_dir: &Path) -> io::Result<PathBuf> {
        let file_info = self.cache.get(&file_id).unwrap();
        let mount_path = self.mounts.get(&file_info.mount_name).unwrap();

        let absolute_path = mount_path.join(&file_info.relative_path);

        Self::minimal_relative_path(&absolute_path, current_dir)
    }

    #[must_use]
    pub fn get_text(&self, node: &Node) -> Option<&str> {
        self.get_span_source(
            node.span.file_id,
            node.span.offset as usize,
            node.span.length as usize,
        )
    }

    #[must_use]
    pub fn get_text_span(&self, span: &Span) -> Option<&str> {
        self.get_span_source(span.file_id, span.offset as usize, span.length as usize)
    }

    #[must_use]
    pub fn get_line(&self, span: &Span, current_dir: &Path) -> Option<FileLineInfo> {
        let relative_file_name = self.get_relative_path_to(span.file_id, current_dir).ok()?;
        let (row, col) = self.get_span_location_utf8(span.file_id, span.offset as usize)?;
        let line = self.get_source_line(span.file_id, row)?;

        Some(FileLineInfo {
            row,
            col,
            line: line.to_string(),
            relative_file_name: relative_file_name.to_str().unwrap().to_string(),
        })
    }

    pub fn set(&mut self, mount_name: &str, relative_path: &Path, contents: &str) -> FileId {
        // Check if file already exists in cache
        if let Some(&existing_file_id) = self.file_cache.get(&(
            mount_name.to_string(),
            relative_path.to_str().unwrap().to_string(),
        )) {
            // File exists, update its contents
            let line_offsets = Self::compute_line_offsets(contents);

            if let Some(file_info) = self.cache.get_mut(&existing_file_id) {
                file_info.contents = contents.to_string();
                file_info.line_offsets = line_offsets;
            }

            existing_file_id
        } else {
            // File doesn't exist, add it as new
            self.add_manual_no_id(mount_name, relative_path, contents)
        }
    }
}

pub struct FileLineInfo {
    pub row: usize,
    pub col: usize,
    pub line: String,
    pub relative_file_name: String,
}

pub struct SourceLineInfo {
    pub line: String,
    pub relative_file_name: String,
}

pub trait SourceMapLookup: Debug {
    fn get_text(&self, node: &Node) -> Option<&str>;
    fn get_text_span(&self, span: &Span) -> Option<&str>;
    fn get_line(&self, span: &Span) -> Option<FileLineInfo>;
    fn get_relative_path(&self, file_id: FileId) -> String;
    fn get_source_line(&self, file_id: FileId, row: usize) -> Option<&str>;
}

#[derive(Debug)]
pub struct SourceMapWrapper<'a> {
    pub source_map: &'a SourceMap,
    pub current_dir: PathBuf,
}

impl SourceMapLookup for SourceMapWrapper<'_> {
    fn get_text(&self, resolved_node: &Node) -> Option<&str> {
        self.source_map.get_text(resolved_node)
    }

    fn get_text_span(&self, span: &Span) -> Option<&str> {
        self.source_map.get_text_span(span)
    }

    fn get_line(&self, span: &Span) -> Option<FileLineInfo> {
        self.source_map.get_line(span, &self.current_dir)
    }

    fn get_relative_path(&self, file_id: FileId) -> String {
        self.source_map
            .get_relative_path_to(file_id, &self.current_dir)
            .unwrap()
            .to_str()
            .unwrap()
            .to_string()
    }

    fn get_source_line(&self, file_id: FileId, line_number: usize) -> Option<&str> {
        self.source_map.get_source_line(file_id, line_number)
    }
}