# Reads and returns a complete file as a string
var readfile = func(file) {
    if ((var st = stat(file)) == nil)
        die("Cannot stat file: " ~ file);
    var sz = st[7];
    var buf = bits.buf(sz);
    read(open(file), buf, sz);
    return buf;
}

# basename(<path>), dirname(<path>)
#
# Work like standard Unix commands: basename returns the file name from a given
# path, and dirname returns the directory part.

var basename = func(path) {
    split("/", string.normpath(path))[-1];
};

var dirname =  func(path) {
    path = string.normpath(path);
    substr(path, 0, size(path) - size(basename(path)));
};

# include(<filename>)
#
# Loads and executes a Nasal file in place. The file is searched for in the
# calling script directory and in standard FG directories (in that order).
#
# Examples:
#
#     io.include("Aircraft/Generic/library.nas");
#     io.include("my_other_file.nas");

var include = func(file) {

    file = string.normpath(file);
    var clr = caller();
    var (ns, fn, fl) = clr;

    var local_file = dirname(fl) ~ file;
    var path = (stat(local_file) != nil)? local_file : resolvepath(file);

    if (path == "") die("File not found: ", file);

    var module = "__" ~ path ~ "__";
    if (contains(ns, module))
        return;

    var code = call(compile, [readfile(path), path], var err = []);
    if (size(err)) {
        if (find("Parse error:", err[0]) < 0)
            die(err[0]);
        else
            die(sprintf("%s\n  in included file: %s", err[0], path));
    }

    ns[module] = "included";
    call(bind(code, ns, fn), [], nil, ns);
}

# Loads Nasal file into namespace and executes it. The namespace
# (module name) is taken from the optional second argument, or
# derived from the Nasal file's name.
#
# Usage:   io.load_nasal(<filename> [, <modulename>]);
#
# Example:
#
#     io.load_nasal(getprop("/sim/fg-root") ~ "/Local/test.nas");
#     io.load_nasal("/tmp/foo.nas", "test");
#
var load_nasal = func(file, module = nil) {
    if (module == nil)
        module = split(".", split("/", file)[-1])[0];

    printlog("info", "loading ", file, " into namespace ", module);

    if (!contains(globals, module))
        globals[module] = {};
    elsif (typeof(globals[module]) != "hash")
        die("io.load_nasal(): namespace '" ~ module ~ "' already in use, but not a hash");

    var code = call(func compile(readfile(file), file), nil, var err = []);
    if (size(err)) {
        if (substr(err[0], 0, 12) == "Parse error:") { # hack around Nasal feature
            var e = split(" at line ", err[0]);
            if (size(e) == 2)
                err[0] = string.join("", [e[0], "\n  at ", file, ", line ", e[1], "\n "]);
        }
        for (var i = 1; (var c = caller(i)) != nil; i += 1)
            err ~= subvec(c, 2, 2);
        debug.printerror(err);
        return 0;
    }
    call(bind(code, globals), nil, nil, globals[module], err);
    debug.printerror(err);
    return !size(err);
}


# Load XML file in FlightGear's native <PropertyList> format.
# If the second, optional target parameter is set, then the properties
# are loaded to this node in the global property tree. Otherwise they
# are returned as a separate props.Node tree. Returns the data as a
# props.Node on success or nil on error.
#
# Usage:   io.read_properties(<filename> [, <props.Node or property-path>]);
#
# Examples:
#
#     var target = props.globals.getNode("/sim/model");
#     io.read_properties("/tmp/foo.xml", target);
#
#     var data = io.read_properties("/tmp/foo.xml", "/sim/model");
#     var data = io.read_properties("/tmp/foo.xml");
#
var read_properties = func(path, target = nil) {
    var args = props.Node.new({ filename: path });
    if (target == nil) {
        var ret = args.getNode("data", 1);
    } elsif (isa(target, props.Node)) {
        args.getNode("targetnode", 1).setValue(target.getPath());
        var ret = target;
    } else {
        args.getNode("targetnode", 1).setValue(target);
        var ret = props.globals.getNode(target, 1);
    }
    return fgcommand("loadxml", args) ? ret : nil;
}

# Load XML file in FlightGear's native <PropertyList> format.
# file will be located in the airport-scenery directories according to
# ICAO and filename, i,e in Airports/I/C/A/ICAO.filename.xml
# If the second, optional target parameter is set, then the properties
# are loaded to this node in the global property tree. Otherwise they
# are returned as a separate props.Node tree. Returns the data as a
# props.Node on success or nil on error.
#
# Usage:   io.read_airport_properties(<icao>, <filename> [, <props.Node or property-path>]);
#
# Examples:
#
#     var data = io.read_properties("KSFO", "rwyuse");
#
var read_airport_properties = func(icao, fname, target = nil) {
    var args = props.Node.new({ filename: fname, icao:icao });
    if (target == nil) {
        var ret = args.getNode("data", 1);
    } elsif (isa(target, props.Node)) {
        args.getNode("targetnode", 1).setValue(target.getPath());
        var ret = target;
    } else {
        args.getNode("targetnode", 1).setValue(target);
        var ret = props.globals.getNode(target, 1);
    }
    return fgcommand("loadxml", args) ? ret : nil;
}

# Write XML file in FlightGear's native <PropertyList> format.
# Returns the filename on success or nil on error. If the source
# is a props.Node that refers to a node in the main tree, then
# the data are directly written from the tree, yielding a more
# accurate result. Otherwise the data need to be copied first,
# which may slightly change node types (FLOAT becomes DOUBLE etc.)
#
# Usage:   io.write_properties(<filename>, <props.Node or property-path>);
#
# Examples:
#
#     var data = props.Node.new({ a:1, b:2, c:{ d:3, e:4 } });
#     io.write_properties("/tmp/foo.xml", data);
#     io.write_properties("/tmp/foo.xml", "/sim/model");
#
var write_properties = func(path, prop) {
    var args = props.Node.new({ filename: path });
    # default attributes of a new node plus the lowest unused bit
    var attr = args.getAttribute() + args.getAttribute("last") * 2;
    props.globals.setAttribute(attr);
    if (isa(prop, props.Node)) {
        for (var root = prop; (var p = root.getParent()) != nil;)
            root = p;
        if (root.getAttribute() == attr)
            args.getNode("sourcenode", 1).setValue(prop.getPath());
        else
            props.copy(prop, args.getNode("data", 1), 1);
    } else {
        args.getNode("sourcenode", 1).setValue(prop);
    }
    return fgcommand("savexml", args) ? path : nil;
}


# The following two functions are for reading generic XML files into
# the property tree and for writing them from there to the disk. The
# built-in fgcommands (load, save, loadxml, savexml) are for FlightGear's
# own <PropertyList> XML files only, as they only handle a limited
# number of very specific attributes. The io.readxml() loader turns
# attributes into regular children with a configurable prefix prepended
# to their name, while io.writexml() turns such nodes back into
# attributes. The two functions have their own limitations, but can
# easily get extended to whichever needs. The underlying parsexml()
# command will handle any XML file.

# Reads an XML file from an absolute path and returns it as property
# tree. All nodes will be of type STRING. Data are only written to
# leafs. Attributes are written as regular nodes with the optional
# prefix prepended to the name. If the prefix is nil, then attributes
# are ignored. Returns nil on error.
#
var readxml = func(path, prefix = "___") {
    var stack = [[{}, ""]];
    var node = props.Node.new();
    var tree = node;           # prevent GC
    var start = func(name, attr) {
        var index = stack[-1][0];
        if (!contains(index, name))
            index[name] = 0;

        node = node.getChild(name, index[name], 1);
        if (prefix != nil)
            foreach (var n; keys(attr))
                node.getNode(prefix ~ n, 1).setValue(attr[n]);

        index[name] += 1;
        append(stack, [{}, ""]);
    }
    var end = func(name) {
        var buf = pop(stack);
        if (!size(buf[0]) and size(buf[1]))
            node.setValue(buf[1]);
        node = node.getParent();
    }
    var data = func(d) stack[-1][1] ~= d;
    return parsexml(path, start, end, data) == nil ? nil : tree;
}


# Writes a property tree as returned by readxml() to a file. Children
# with name starting with <prefix> are again turned into attributes of
# their parent. <node> must contain exactly one child, which will
# become the XML file's outermost element.
#
var writexml = func(path, node, indent = "\t", prefix = "___") {
    var root = node.getChildren();
    if (!size(root))
        die("writexml(): tree doesn't have a root node");
    if (substr(path, -4) != ".xml")
        path ~= ".xml";
    var file = open(path, "w");
    write(file, "<?xml version=\"1.0\"?>\n\n");
    var writenode = func(n, ind = "") {
        var name = n.getName();
        var name_attr = name;
        var children = [];
        foreach (var c; n.getChildren()) {
            var a = c.getName();
            if (substr(a, 0, size(prefix)) == prefix)
                name_attr ~= " " ~ substr(a, size(prefix)) ~ '="' ~  c.getValue() ~ '"';
            else
                append(children, c);
        }
        if (size(children)) {
            write(file, ind ~ "<" ~ name_attr ~ ">\n");
            foreach (var c; children)
                writenode(c, ind ~ indent);
            write(file, ind ~ "</" ~ name ~ ">\n");
        } elsif ((var value = n.getValue()) != nil) {
            write(file, ind ~ "<" ~ name_attr ~ ">" ~ value ~ "</" ~ name ~ ">\n");
        } else {
            write(file, ind ~ "<" ~ name_attr ~ "/>\n");
        }
    }
    writenode(root[0]);
    close(file);
    if (size(root) != 1)
        die("writexml(): tree has more than one root node");
}