/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef shell_jsoptparse_h
#define shell_jsoptparse_h

#include <stdio.h>

#include "jsalloc.h"
#include "jsutil.h"

#include "js/Vector.h"

namespace js {
namespace cli {

namespace detail {

struct BoolOption;
struct MultiStringOption;
struct ValuedOption;
struct StringOption;
struct IntOption;

enum OptionKind
{
    OptionKindBool,
    OptionKindString,
    OptionKindInt,
    OptionKindMultiString,
    OptionKindInvalid
};

struct Option
{
    const char* longflag;
    const char* help;
    OptionKind  kind;
    char        shortflag;
    bool        terminatesOptions;

    Option(OptionKind kind, char shortflag, const char* longflag, const char* help)
      : longflag(longflag), help(help), kind(kind), shortflag(shortflag), terminatesOptions(false)
    {}

    virtual ~Option() = 0;

    void setTerminatesOptions(bool enabled) { terminatesOptions = enabled; }
    bool getTerminatesOptions() const { return terminatesOptions; }

    virtual bool isValued() const { return false; }

    /* Only some valued options are variadic (like MultiStringOptions). */
    virtual bool isVariadic() const { return false; }

    /*
     * For arguments, the shortflag field is used to indicate whether the
     * argument is optional.
     */
    bool isOptional() { return shortflag; }

    void setFlagInfo(char shortflag, const char* longflag, const char* help) {
        this->shortflag = shortflag;
        this->longflag = longflag;
        this->help = help;
    }

    ValuedOption* asValued();
    const ValuedOption* asValued() const;

#define OPTION_CONVERT_DECL(__cls) \
    bool is##__cls##Option() const; \
    __cls##Option* as##__cls##Option(); \
    const __cls##Option* as##__cls##Option() const;

    OPTION_CONVERT_DECL(Bool)
    OPTION_CONVERT_DECL(String)
    OPTION_CONVERT_DECL(Int)
    OPTION_CONVERT_DECL(MultiString)
};

inline Option::~Option() {}

struct BoolOption : public Option
{
    size_t  argno;
    bool    value;

    BoolOption(char shortflag, const char* longflag, const char* help)
      : Option(OptionKindBool, shortflag, longflag, help), value(false)
    {}

    virtual ~BoolOption() {}
};

struct ValuedOption : public Option
{
    const char* metavar;

    ValuedOption(OptionKind kind, char shortflag, const char* longflag, const char* help,
                 const char* metavar)
      : Option(kind, shortflag, longflag, help), metavar(metavar)
    {}

    virtual ~ValuedOption() = 0;
    virtual bool isValued() const { return true; }
};

inline ValuedOption::~ValuedOption() {}

struct StringOption : public ValuedOption
{
    const char* value;

    StringOption(char shortflag, const char* longflag, const char* help, const char* metavar)
      : ValuedOption(OptionKindString, shortflag, longflag, help, metavar), value(nullptr)
    {}

    virtual ~StringOption() {}
};

struct IntOption : public ValuedOption
{
    int value;

    IntOption(char shortflag, const char* longflag, const char* help, const char* metavar,
              int defaultValue)
      : ValuedOption(OptionKindInt, shortflag, longflag, help, metavar), value(defaultValue)
    {}

    virtual ~IntOption() {}
};

struct StringArg
{
    char*   value;
    size_t  argno;

    StringArg(char* value, size_t argno) : value(value), argno(argno) {}
};

struct MultiStringOption : public ValuedOption
{
    Vector<StringArg, 0, SystemAllocPolicy> strings;

    MultiStringOption(char shortflag, const char* longflag, const char* help, const char* metavar)
      : ValuedOption(OptionKindMultiString, shortflag, longflag, help, metavar)
    {}

    virtual ~MultiStringOption() {}

    virtual bool isVariadic() const { return true; }
};

} /* namespace detail */

class MultiStringRange
{
    typedef detail::StringArg StringArg;
    const StringArg* cur;
    const StringArg* end;

  public:
    explicit MultiStringRange(const StringArg* cur, const StringArg* end)
      : cur(cur), end(end) {
        MOZ_ASSERT(end - cur >= 0);
    }

    bool empty() const { return cur == end; }
    void popFront() { MOZ_ASSERT(!empty()); ++cur; }
    char* front() const { MOZ_ASSERT(!empty()); return cur->value; }
    size_t argno() const { MOZ_ASSERT(!empty()); return cur->argno; }
};

/*
 * Builder for describing a command line interface and parsing the resulting
 * specification.
 *
 * - A multi-option is an option that can appear multiple times and still
 *   parse as valid command line arguments.
 * - An "optional argument" is supported for backwards compatibility with prior
 *   command line interface usage. Once one optional argument has been added,
 *   *only* optional arguments may be added.
 */
class OptionParser
{
  public:
    enum Result
    {
        Okay = 0,
        Fail,       /* As in, allocation fail. */
        ParseError, /* Successfully parsed but with an error. */
        EarlyExit   /* Successfully parsed but exits the program,
                     * for example with --help and --version. */
    };

  private:
    typedef Vector<detail::Option*, 0, SystemAllocPolicy> Options;
    typedef detail::Option Option;
    typedef detail::BoolOption BoolOption;

    Options     options;
    Options     arguments;
    BoolOption  helpOption;
    BoolOption  versionOption;
    const char* usage;
    const char* version;
    const char* descr;
    size_t      descrWidth;
    size_t      helpWidth;
    size_t      nextArgument;

    // If '--' is passed, all remaining arguments should be interpreted as the
    // argument at index 'restArgument'. Defaults to the next unassigned
    // argument.
    int         restArgument;

    static const char prognameMeta[];

    Option* findOption(char shortflag);
    const Option* findOption(char shortflag) const;
    Option* findOption(const char* longflag);
    const Option* findOption(const char* longflag) const;
    int findArgumentIndex(const char* name) const;
    Option* findArgument(const char* name);
    const Option* findArgument(const char* name) const;

    Result error(const char* fmt, ...);
    Result extractValue(size_t argc, char** argv, size_t* i, char** value);
    Result handleArg(size_t argc, char** argv, size_t* i, bool* optsAllowed);
    Result handleOption(Option* opt, size_t argc, char** argv, size_t* i, bool* optsAllowed);

  public:
    explicit OptionParser(const char* usage)
      : helpOption('h', "help", "Display help information"),
        versionOption('v', "version", "Display version information and exit"),
        usage(usage), version(nullptr), descr(nullptr), descrWidth(80), helpWidth(80),
        nextArgument(0), restArgument(-1)
    {}

    ~OptionParser();

    Result parseArgs(int argc, char** argv);
    Result printHelp(const char* progname);
    Result printVersion();

    /* Metadata */

    void setVersion(const char* v) { version = v; }
    void setHelpWidth(size_t width) { helpWidth = width; }
    void setDescriptionWidth(size_t width) { descrWidth = width; }
    void setDescription(const char* description) { descr = description; }
    void setHelpOption(char shortflag, const char* longflag, const char* help);
    void setArgTerminatesOptions(const char* name, bool enabled);
    void setArgCapturesRest(const char* name);

    /* Arguments: no further arguments may be added after a variadic argument. */

    bool addOptionalStringArg(const char* name, const char* help);
    bool addOptionalMultiStringArg(const char* name, const char* help);

    const char* getStringArg(const char* name) const;
    MultiStringRange getMultiStringArg(const char* name) const;

    /* Options */

    bool addBoolOption(char shortflag, const char* longflag, const char* help);
    bool addStringOption(char shortflag, const char* longflag, const char* help,
                         const char* metavar);
    bool addIntOption(char shortflag, const char* longflag, const char* help,
                      const char* metavar, int defaultValue);
    bool addMultiStringOption(char shortflag, const char* longflag, const char* help,
                              const char* metavar);
    bool addOptionalVariadicArg(const char* name);

    int getIntOption(char shortflag) const;
    int getIntOption(const char* longflag) const;
    const char* getStringOption(char shortflag) const;
    const char* getStringOption(const char* longflag) const;
    bool getBoolOption(char shortflag) const;
    bool getBoolOption(const char* longflag) const;
    MultiStringRange getMultiStringOption(char shortflag) const;
    MultiStringRange getMultiStringOption(const char* longflag) const;

    /*
     * Return whether the help option was present (and thus help was already
     * displayed during parse_args).
     */
    bool getHelpOption() const;
};

} /* namespace cli */
} /* namespace js */

#endif /* shell_jsoptparse_h */