using System.Collections.Generic;

using System.Text;

using System.Threading;

using System.Threading.Tasks;

namespace Microsoft.Python.Parsing.Ast {

public class FString : Expression {

private readonly Node[] _children;

private readonly string _openQuotes;

public FString(Node[] children, string openQuotes, string unparsed) {

_children = children;

_openQuotes = openQuotes;

Unparsed = unparsed;

}

public override IEnumerable<Node> GetChildNodes() {

return _children;

}

public readonly string Unparsed;

public override string NodeName => "f-string expression";

public override void Walk(PythonWalker walker) {

if (walker.Walk(this)) {

foreach (var child in _children) {

child.Walk(walker);

}

}

walker.PostWalk(this);

}

public async override Task WalkAsync(PythonWalkerAsync walker, CancellationToken cancellationToken = default) {

if (await walker.WalkAsync(this, cancellationToken)) {

foreach (var child in _children) {

await child.WalkAsync(walker, cancellationToken);

}

}

await walker.PostWalkAsync(this, cancellationToken);

}

internal override void AppendCodeString(StringBuilder res, PythonAst ast, CodeFormattingOptions format) {

var verbatimPieces = this.GetVerbatimNames(ast);

var verbatimComments = this.GetListWhiteSpace(ast);

if (verbatimPieces != null) {

// string+ / bytes+, such as "abc" "abc", which can spawn multiple lines, and

// have comments in between the peices.

for (var i = 0; i < verbatimPieces.Length; i++) {

if (verbatimComments != null && i < verbatimComments.Length) {

format.ReflowComment(res, verbatimComments[i]);

}

res.Append(verbatimPieces[i]);

}

} else {

format.ReflowComment(res, this.GetPreceedingWhiteSpaceDefaultNull(ast));

if (this.GetExtraVerbatimText(ast) != null) {

res.Append(this.GetExtraVerbatimText(ast));

} else {

RecursiveAppendRepr(res, ast, format);

}

}

}

private void RecursiveAppendRepr(StringBuilder res, PythonAst ast, CodeFormattingOptions format) {

res.Append('f');

res.Append(_openQuotes);

foreach (var child in _children) {

AppendChild(res, ast, format, child);

}

res.Append(_openQuotes);

}

private static void AppendChild(StringBuilder res, PythonAst ast, CodeFormattingOptions format, Node child) {

if (child is ConstantExpression expr) {

// Non-Verbatim AppendCodeString for ConstantExpression adds quotes around string

// Remove those quotes

var childStrBuilder = new StringBuilder();

child.AppendCodeString(childStrBuilder, ast, format);

res.Append(childStrBuilder.ToString().Trim('\''));

} else {

child.AppendCodeString(res, ast, format);

}

}

}

}