package org.javacs;

import com.sun.source.tree.*;

import com.sun.source.util.JavacTask;

import com.sun.source.util.SourcePositions;

import com.sun.source.util.TreeScanner;

import com.sun.source.util.Trees;

import com.sun.tools.javac.tree.JCTree;

import com.sun.tools.javac.util.List;

import java.io.IOException;

import java.io.Reader;

import javax.tools.JavaFileObject;

/** Fix up the tree to make it easier to autocomplete, index */

class TreePruner {

private final JavacTask task;

TreePruner(JavacTask task) {

this.task = task;

}

void removeNonCursorMethodBodies(CompilationUnitTree source, int line, int column) {

long offset = source.getLineMap().getPosition(line, column);

doRemoveNonCursorMethodBodies(source, offset);

}

void removeAllMethodBodies(CompilationUnitTree source) {

doRemoveNonCursorMethodBodies(source, -1);

}

private void doRemoveNonCursorMethodBodies(CompilationUnitTree source, long offset) {

SourcePositions sourcePositions = Trees.instance(task).getSourcePositions();

class Pruner extends TreeScanner<Void, Void> {

@Override

public Void visitBlock(BlockTree node, Void aVoid) {

if (containsCursor(node)) super.visitBlock(node, aVoid);

else {

JCTree.JCBlock impl = (JCTree.JCBlock) node;

impl.stats = List.nil();

}

return null;

}

boolean containsCursor(Tree leaf) {

long start = sourcePositions.getStartPosition(source, leaf);

long end = sourcePositions.getEndPosition(source, leaf);

return start <= offset && offset <= end;

}

@Override

public Void visitErroneous(ErroneousTree node, Void nothing) {

return super.scan(node.getErrorTrees(), nothing);

}

}

new Pruner().scan(source, null);

}

/** Remove all statements after the statement the cursor is in */

void removeStatementsAfterCursor(CompilationUnitTree source, int line, int column) {

SourcePositions sourcePositions = Trees.instance(task).getSourcePositions();

long offset = source.getLineMap().getPosition(line, column);

class Pruner extends TreeScanner<Void, Void> {

@Override

public Void visitBlock(BlockTree node, Void aVoid) {

JCTree.JCBlock impl = (JCTree.JCBlock) node;

impl.stats = pruneStatements(impl.stats);

return super.visitBlock(node, aVoid);

}

@Override

public Void visitSwitch(SwitchTree node, Void aVoid) {

JCTree.JCSwitch impl = (JCTree.JCSwitch) node;

impl.cases = pruneStatements(impl.cases);

return super.visitSwitch(node, aVoid);

}

@Override

public Void visitCase(CaseTree node, Void aVoid) {

JCTree.JCCase impl = (JCTree.JCCase) node;

impl.stats = pruneStatements(impl.stats);

return super.visitCase(node, aVoid);

}

private <T extends Tree> List<T> pruneStatements(List<T> stats) {

int countStatements = 0;

boolean foundCursor = false;

// Scan up to statement containing cursor

while (countStatements < stats.size()) {

T s = stats.get(countStatements);

if (containsCursor(s)) foundCursor = true;

else if (foundCursor) break;

else this.scan(s, null);

countStatements++;

}

// Remove all statements after statement containing cursor

return stats.take(countStatements);

}

boolean containsCursor(Tree leaf) {

long start = sourcePositions.getStartPosition(source, leaf);

long end = sourcePositions.getEndPosition(source, leaf);

return start <= offset && offset <= end;

}

@Override

public Void visitErroneous(ErroneousTree node, Void nothing) {

return super.scan(node.getErrorTrees(), nothing);

}

}

new Pruner().scan(source, null);

}

/**

* Insert ';' after the users cursor so we recover from parse errors in a helpful way when doing

* autocomplete.

*/

static JavaFileObject putSemicolonAfterCursor(

JavaFileObject file, int cursorLine, int cursorCharacter) {

try (Reader reader = file.openReader(true)) {

StringBuilder acc = new StringBuilder();

int line = 1, character = 1;

// Go to the cursor

while (line < cursorLine || character < cursorCharacter) {

int next = reader.read();

if (next == -1)

throw new RuntimeException(

"End of file "

+ file

+ " before cursor "

+ cursorLine

+ ":"

+ cursorCharacter);

else if (next == '\n') {

line++;

character = 1;

} else character++;

acc.append((char) next);

}

// Go to the end of the line

while (true) {

int next = reader.read();

if (next == -1 || next == '\n') break;

acc.append((char) next);

}

acc.append(";\n");

for (int next = reader.read(); next > 0; next = reader.read()) {

acc.append((char) next);

}

return new StringFileObject(acc.toString(), file.toUri());

} catch (IOException e) {

throw ShowMessageException.error("Error reading " + file, e);

}

}

}