const std = @import("std");

const ast = std.zig.ast;

/// REALLY BAD CODE, PLEASE DON'T USE THIS!!!!!!! (only for testing)
pub fn getFunctionByName(tree: *ast.Tree, name: []const u8) ?*ast.Node.FnProto {
    var decls = tree.root_node.decls.iterator(0);
    while (decls.next()) |decl_ptr| {
        var decl = decl_ptr.*;
        switch (decl.id) {
            .FnProto => {
                const func = decl.cast(ast.Node.FnProto).?;
                if (std.mem.eql(u8, tree.tokenSlice(func.name_token.?), name)) return func;
            },
            else => {}
        }
    }

    return null;
}

/// Gets a function's doc comments, caller must free memory when a value is returned
/// Like:
///```zig
///var comments = getFunctionDocComments(allocator, tree, func);
///defer if (comments) |comments_pointer| allocator.free(comments_pointer);
///```
pub fn getDocComments(allocator: *std.mem.Allocator, tree: *ast.Tree, node: *ast.Node) !?[]const u8 {
    switch (node.id) {
        .FnProto => {
            const func = node.cast(ast.Node.FnProto).?;
            if (func.doc_comments) |doc_comments| {
                var doc_it = doc_comments.lines.iterator(0);
                var lines = std.ArrayList([]const u8).init(allocator);
                defer lines.deinit();

                while (doc_it.next()) |doc_comment| {
                    _ = try lines.append(std.fmt.trim(tree.tokenSlice(doc_comment.*)[3..]));
                }

                return try std.mem.join(allocator, "\n", lines.items);
            } else {
                return null;
            }
        },
        .VarDecl => {
            const var_decl = node.cast(ast.Node.VarDecl).?;
            if (var_decl.doc_comments) |doc_comments| {
                var doc_it = doc_comments.lines.iterator(0);
                var lines = std.ArrayList([]const u8).init(allocator);
                defer lines.deinit();

                while (doc_it.next()) |doc_comment| {
                    _ = try lines.append(std.fmt.trim(tree.tokenSlice(doc_comment.*)[3..]));
                }

                return try std.mem.join(allocator, "\n", lines.items);
            } else {
                return null;
            }
        },
        else => return null
    }
}

/// Gets a function signature (keywords, name, return value)
pub fn getFunctionSignature(tree: *ast.Tree, func: *ast.Node.FnProto) []const u8 {
    const start = tree.tokens.at(func.firstToken()).start;
    const end = tree.tokens.at(switch (func.return_type) {
        .Explicit, .InferErrorSet => |node| node.lastToken()
    }).end;
    return tree.source[start..end];
}

/// Gets a function snippet insert text
pub fn getFunctionSnippet(allocator: *std.mem.Allocator, tree: *ast.Tree, func: *ast.Node.FnProto) ![]const u8 {
    const name_tok = func.name_token orelse unreachable;

    var buffer = std.ArrayList(u8).init(allocator);
    try buffer.ensureCapacity(128);

    try buffer.appendSlice(tree.tokenSlice(name_tok));
    try buffer.append('(');

    var buf_stream = buffer.outStream();

    var param_num = @as(usize, 1);
    var param_it = func.params.iterator(0);
    while (param_it.next()) |param_ptr| : (param_num += 1) {
        const param = param_ptr.*;

        if (param_num != 1) try buffer.appendSlice(", ${")
        else try buffer.appendSlice("${");

        try buf_stream.print("{}:", .{param_num});
        var curr_tok = param.firstToken();
        const end_tok = param.lastToken();

        var first_tok = true;
        while (curr_tok <= end_tok) : (curr_tok += 1) {
            try buffer.appendSlice(tree.tokenSlice(curr_tok));
            if (!first_tok and curr_tok != end_tok) try buffer.append(' ')
            else first_tok = false;
        }

        try buffer.append('}');
    }
    try buffer.append(')');

    return buffer.toOwnedSlice();
}

/// Gets a function signature (keywords, name, return value)
pub fn getVariableSignature(tree: *ast.Tree, var_decl: *ast.Node.VarDecl) []const u8 {
    const start = tree.tokens.at(var_decl.firstToken()).start;
    const end = tree.tokens.at(var_decl.semicolon_token).start;
    // var end = 
        // if (var_decl.init_n) |body| tree.tokens.at(body.firstToken()).start
        // else tree.tokens.at(var_decl.name_token).end;
    return tree.source[start..end];
}

// STYLE

pub fn isCamelCase(name: []const u8) bool {
    return !std.ascii.isUpper(name[0]) and std.mem.indexOf(u8, name, "_") == null;
}

pub fn isPascalCase(name: []const u8) bool {
    return std.ascii.isUpper(name[0]) and std.mem.indexOf(u8, name, "_") == null;
}