php-lsp 0.18.1

use std::collections::HashMap;

use tower_lsp::lsp_types::{Position, Range, TextEdit, Url, WorkspaceEdit};

use crate::document::ast::ParsedDoc;
use crate::navigation::walk::collect_var_refs_in_scope;
use crate::text::utf16_code_units;

/// Narrow `range` to the last whole-word, case-sensitive occurrence of
/// `word` inside it — or reject the location entirely.
///
/// mir's posting spans cover the full written name — a qualified usage
/// (`\App\Widget`), a `use` import item (`App\Widget as W`), or a property
/// declaration (`$count`) — while a rename must replace only the renamed
/// token: the final path segment, or the alias when that is what's being
/// renamed. `None` means the span doesn't contain the word at all (an
/// aliased usage site, or a name differing only in case — mir resolves
/// per PHP's case-insensitive semantics, but rename edits follow the
/// case-sensitive editor convention) and must not be edited.
pub fn narrow_range_to_word(source: &str, range: Range, word: &str) -> Option<Range> {
    if word.is_empty() || range.start.line != range.end.line {
        return None;
    }
    let line = source.lines().nth(range.start.line as usize)?;
    // UTF-16 column → byte offset within the line.
    let byte_at_col = |col: u32| -> Option<usize> {
        let mut u16s: u32 = 0;
        if col == 0 {
            return Some(0);
        }
        for (i, ch) in line.char_indices() {
            if u16s == col {
                return Some(i);
            }
            u16s += ch.len_utf16() as u32;
        }
        (u16s >= col).then_some(line.len())
    };
    let start_b = byte_at_col(range.start.character)?;
    let end_b = byte_at_col(range.end.character)?;
    let slice = line.get(start_b..end_b)?;
    if slice == word {
        return Some(range);
    }

    let is_word_char = |c: char| c.is_alphanumeric() || c == '_';
    let mut found: Option<usize> = None;
    let mut search = 0usize;
    while let Some(pos) = slice[search..].find(word) {
        let abs = search + pos;
        let before_ok = abs == 0 || !slice[..abs].chars().next_back().is_some_and(is_word_char);
        let after = abs + word.len();
        let after_ok =
            after >= slice.len() || !slice[after..].chars().next().is_some_and(is_word_char);
        if before_ok && after_ok {
            found = Some(abs);
        }
        search = after.max(abs + 1);
    }
    let off = found?;

    let new_start = range.start.character + utf16_code_units(&slice[..off]);
    Some(Range {
        start: Position {
            line: range.start.line,
            character: new_start,
        },
        end: Position {
            line: range.start.line,
            character: new_start + utf16_code_units(word),
        },
    })
}

/// Returns the range of the word at `position` if it's a renameable symbol.
/// Used for `textDocument/prepareRename`.
pub fn prepare_rename(source: &str, position: Position) -> Option<Range> {
    use crate::text::word_at_position;
    let word = word_at_position(source, position)?;
    if word.contains('\\') {
        return None;
    }
    // PHP keywords cannot be renamed; return None so editors disable the action.
    if is_php_keyword(&word) {
        return None;
    }
    // PHP superglobals ($_GET, $_POST, etc.) are part of the language runtime;
    // renaming them breaks code, so we disable the action.
    if is_superglobal(&word) {
        return None;
    }
    let line = source.lines().nth(position.line as usize)?;
    let col = position.character as usize;
    let chars: Vec<char> = line.chars().collect();
    // `is_word` intentionally excludes `$` so the range covers only the bare
    // identifier name (not the sigil). `word_at` may return `$var` with the `$`,
    // so we strip it before computing the range length to avoid an off-by-one.
    let is_word = |c: char| c.is_alphanumeric() || c == '_';

    // Find the character index at or before the cursor position (in UTF-16 code units)
    let mut utf16_col = 0usize;
    let mut char_idx = 0usize;
    for (i, ch) in chars.iter().enumerate() {
        // Check if cursor is within this character's UTF-16 span
        let char_width = ch.len_utf16();
        if utf16_col + char_width > col {
            char_idx = i;
            break;
        }
        utf16_col += char_width;
        char_idx = i + 1;
    }

    // Find the start of the word by walking backwards
    let mut left = char_idx;
    while left > 0 && is_word(chars[left - 1]) {
        left -= 1;
    }

    let bare_word = word.trim_start_matches('$');
    let start_utf16: u32 = chars[..left].iter().map(|c| c.len_utf16() as u32).sum();
    let end_utf16: u32 = start_utf16 + utf16_code_units(bare_word);
    Some(Range {
        start: Position {
            line: position.line,
            character: start_utf16,
        },
        end: Position {
            line: position.line,
            character: end_utf16,
        },
    })
}

fn is_php_keyword(word: &str) -> bool {
    matches!(
        word,
        "abstract"
            | "and"
            | "array"
            | "as"
            | "bool"
            | "break"
            | "callable"
            | "case"
            | "catch"
            | "class"
            | "clone"
            | "const"
            | "continue"
            | "declare"
            | "default"
            | "die"
            | "do"
            | "echo"
            | "else"
            | "elseif"
            | "empty"
            | "enddeclare"
            | "endfor"
            | "endforeach"
            | "endif"
            | "endswitch"
            | "endwhile"
            | "enum"
            | "eval"
            | "exit"
            | "extends"
            | "false"
            | "final"
            | "finally"
            | "float"
            | "fn"
            | "for"
            | "foreach"
            | "function"
            | "global"
            | "goto"
            | "if"
            | "implements"
            | "include"
            | "include_once"
            | "instanceof"
            | "insteadof"
            | "int"
            | "interface"
            | "isset"
            | "iterable"
            | "list"
            | "match"
            | "mixed"
            | "namespace"
            | "never"
            | "new"
            | "null"
            | "object"
            | "or"
            | "parent"
            | "print"
            | "private"
            | "protected"
            | "public"
            | "readonly"
            | "require"
            | "require_once"
            | "return"
            | "self"
            | "static"
            | "string"
            | "switch"
            | "throw"
            | "trait"
            | "true"
            | "try"
            | "use"
            | "var"
            | "void"
            | "while"
            | "xor"
            | "yield"
            | "__CLASS__"
            | "__DIR__"
            | "__FILE__"
            | "__FUNCTION__"
            | "__LINE__"
            | "__METHOD__"
            | "__NAMESPACE__"
            | "__TRAIT__"
    )
}

fn is_superglobal(word: &str) -> bool {
    matches!(
        word,
        "$_GET"
            | "$_POST"
            | "$_REQUEST"
            | "$_FILES"
            | "$_COOKIE"
            | "$_SESSION"
            | "$_SERVER"
            | "$_ENV"
            | "$GLOBALS"
            | "$this"
    )
}

/// Rename a `$variable` (or parameter) within its enclosing function/method scope.
/// Only produces edits within the single document `uri`; variables don't cross files.
pub fn rename_variable(
    var_name: &str,
    new_name: &str,
    uri: &Url,
    doc: &ParsedDoc,
    position: Position,
) -> WorkspaceEdit {
    let bare = var_name.trim_start_matches('$');
    let new_bare = new_name.trim_start_matches('$');
    let new_text = format!("${new_bare}");

    let stmts = &doc.program().stmts;
    let sv = doc.view();
    let byte_off = sv.byte_of_position(position) as usize;

    let mut spans = Vec::new();
    collect_var_refs_in_scope(stmts, bare, byte_off, &mut spans);

    let mut seen = std::collections::HashSet::new();
    let mut edits: Vec<TextEdit> = spans
        .into_iter()
        .filter_map(|(span, _)| {
            let start = sv.position_of(span.start);
            let end = sv.position_of(span.end);
            seen.insert((start.line, start.character))
                .then_some(TextEdit {
                    range: Range { start, end },
                    new_text: new_text.clone(),
                })
        })
        .collect();
    edits.sort_by_key(|e| (e.range.start.line, e.range.start.character));

    let mut changes = HashMap::new();
    if !edits.is_empty() {
        changes.insert(uri.clone(), edits);
    }

    WorkspaceEdit {
        changes: if changes.is_empty() {
            None
        } else {
            Some(changes)
        },
        ..Default::default()
    }
}