#ifndef LIBCUBESCRIPT_CUBESCRIPT_HH
#define LIBCUBESCRIPT_CUBESCRIPT_HH

#include <cstring>
#include <vector>
#include <optional>
#include <functional>
#include <type_traits>
#include <algorithm>
#include <utility>

#include "cubescript_conf.hh"

#if defined(__CYGWIN__) || (defined(_WIN32) && !defined(_XBOX_VER))
#  ifdef LIBCUBESCRIPT_DLL
#    ifdef LIBCUBESCRIPT_BUILD
#      define LIBCUBESCRIPT_EXPORT __declspec(dllexport)
#    else
#      define LIBCUBESCRIPT_EXPORT __declspec(dllimport)
#    endif
#  else
#    define LIBCUBESCRIPT_EXPORT
#  endif
#  define LIBCUBESCRIPT_LOCAL
#else
#  if defined(__GNUC__) && (__GNUC__ >= 4)
#    define LIBCUBESCRIPT_EXPORT __attribute__((visibility("default")))
#    define LIBCUBESCRIPT_LOCAL __attribute__((visibility("hidden")))
#  else
#    define LIBCUBESCRIPT_EXPORT
#    define LIBCUBESCRIPT_LOCAL
#  endif
#endif

namespace cscript {

static_assert(std::is_integral_v<cs_int>, "cs_int must be integral");
static_assert(std::is_signed_v<cs_int>, "cs_int must be signed");
static_assert(std::is_floating_point_v<cs_float>, "cs_float must be floating point");

struct cs_internal_error: std::runtime_error {
    using std::runtime_error::runtime_error;
};

enum {
    CS_IDF_PERSIST    = 1 << 0,
    CS_IDF_OVERRIDE   = 1 << 1,
    CS_IDF_HEX        = 1 << 2,
    CS_IDF_READONLY   = 1 << 3,
    CS_IDF_OVERRIDDEN = 1 << 4,
    CS_IDF_UNKNOWN    = 1 << 5,
    CS_IDF_ARG        = 1 << 6
};

struct cs_bcode;
struct cs_value;
struct cs_state;
struct cs_shared_state;

struct LIBCUBESCRIPT_EXPORT cs_bcode_ref {
    cs_bcode_ref():
        p_code(nullptr)
    {}
    cs_bcode_ref(cs_bcode *v);
    cs_bcode_ref(cs_bcode_ref const &v);
    cs_bcode_ref(cs_bcode_ref &&v):
        p_code(v.p_code)
    {
        v.p_code = nullptr;
    }

    ~cs_bcode_ref();

    cs_bcode_ref &operator=(cs_bcode_ref const &v);
    cs_bcode_ref &operator=(cs_bcode_ref &&v);

    operator bool() const { return p_code != nullptr; }
    operator cs_bcode *() const { return p_code; }

private:
    cs_bcode *p_code;
};

LIBCUBESCRIPT_EXPORT bool cs_code_is_empty(cs_bcode *code);

struct LIBCUBESCRIPT_EXPORT cs_strref {
    friend struct cs_value;
    /* FIXME: eliminate this */
    friend inline cs_strref cs_make_strref(char const *p, cs_shared_state &cs);

    cs_strref() = delete;
    cs_strref(cs_shared_state &cs, std::string_view str);
    cs_strref(cs_state &cs, std::string_view str);

    cs_strref(cs_strref const &ref);

    ~cs_strref();

    cs_strref &operator=(cs_strref const &ref);

    operator std::string_view() const;

    std::size_t size() const {
        return std::string_view{*this}.size();
    }
    std::size_t length() const {
        return std::string_view{*this}.length();
    }

    char const *data() const {
        return std::string_view{*this}.data();
    }

    bool operator==(cs_strref const &s) const;

private:
    /* for internal use only */
    cs_strref(char const *p, cs_shared_state &cs);

    cs_shared_state *p_state;
    char const *p_str;
};

enum class cs_value_type {
    NONE = 0, INT, FLOAT, STRING, CODE, IDENT
};

struct LIBCUBESCRIPT_EXPORT cs_value {
    cs_value() = delete;
    ~cs_value();

    cs_value(cs_state &);
    cs_value(cs_shared_state &);

    cs_value(cs_value const &);
    cs_value(cs_value &&v);

    cs_value &operator=(cs_value const &);
    cs_value &operator=(cs_value &&);

    cs_value_type get_type() const;

    void set_int(cs_int val);
    void set_float(cs_float val);
    void set_str(std::string_view val);
    void set_str(cs_strref const &val);
    void set_none();
    void set_code(cs_bcode *val);
    void set_ident(cs_ident *val);

    cs_strref get_str() const;
    cs_int get_int() const;
    cs_float get_float() const;
    cs_bcode *get_code() const;
    cs_ident *get_ident() const;
    void get_val(cs_value &r) const;

    bool get_bool() const;

    void force_none();
    cs_float force_float();
    cs_int force_int();
    std::string_view force_str();

    bool code_is_empty() const;

private:
    template<typename T>
    struct stor_t {
        cs_shared_state *state;
        T val;
    };

    cs_shared_state *state() const {
        return reinterpret_cast<stor_t<void *> const *>(&p_stor)->state;
    }

    std::aligned_union_t<1,
        stor_t<cs_int>,
        stor_t<cs_float>,
        stor_t<void *>,
        cs_strref
    > p_stor;
    cs_value_type p_type;
};

struct cs_ident_stack {
    cs_value val_s;
    cs_ident_stack *next;

    cs_ident_stack(cs_state &cs): val_s{cs}, next{nullptr} {}
};

struct cs_error;
struct cs_gen_state;

enum class cs_ident_type {
    IVAR = 0, FVAR, SVAR, COMMAND, ALIAS, SPECIAL
};

struct cs_var;
struct cs_ivar;
struct cs_fvar;
struct cs_svar;
struct cs_alias;
struct cs_command;

struct LIBCUBESCRIPT_EXPORT cs_ident {
    friend struct cs_state;
    friend struct cs_shared_state;

    cs_ident() = delete;
    cs_ident(cs_ident const &) = delete;
    cs_ident(cs_ident &&) = delete;

    /* trigger destructors for all inherited members properly */
    virtual ~cs_ident() {};

    cs_ident &operator=(cs_ident const &) = delete;
    cs_ident &operator=(cs_ident &&) = delete;

    cs_ident_type get_type() const;
    std::string_view get_name() const;
    int get_flags() const;
    int get_index() const;

    bool is_alias() const;
    cs_alias *get_alias();
    cs_alias const *get_alias() const;

    bool is_command() const;
    cs_command *get_command();
    cs_command const *get_command() const;

    bool is_special() const;

    bool is_var() const;
    cs_var *get_var();
    cs_var const *get_var() const;

    bool is_ivar() const;
    cs_ivar *get_ivar();
    cs_ivar const *get_ivar() const;

    bool is_fvar() const;
    cs_fvar *get_fvar();
    cs_fvar const *get_fvar() const;

    bool is_svar() const;
    cs_svar *get_svar();
    cs_svar const *get_svar() const;

    int get_type_raw() const {
        return p_type;
    }

protected:
    cs_ident(cs_ident_type tp, cs_strref name, int flags = 0);

    cs_strref p_name;
    /* represents the cs_ident_type above, but internally it has a wider variety
     * of values, so it's an int here (maps to an internal enum)
     */
    int p_type, p_flags;

private:
    int p_index = -1;
};

struct LIBCUBESCRIPT_EXPORT cs_var: cs_ident {
    friend struct cs_state;
    friend struct cs_shared_state;

protected:
    cs_var(cs_ident_type tp, cs_strref name, cs_var_cb func, int flags = 0);

private:
    cs_var_cb cb_var;

    void changed(cs_state &cs) {
        if (cb_var) {
            cb_var(cs, *this);
        }
    }
};

struct LIBCUBESCRIPT_EXPORT cs_ivar: cs_var {
    friend struct cs_state;
    friend struct cs_shared_state;

    cs_int get_val_min() const;
    cs_int get_val_max() const;

    cs_int get_value() const;
    void set_value(cs_int val);

private:
    cs_ivar(
        cs_strref n, cs_int m, cs_int x, cs_int v, cs_var_cb f, int flags
    );

    cs_int p_storage, p_minval, p_maxval, p_overrideval;
};

struct LIBCUBESCRIPT_EXPORT cs_fvar: cs_var {
    friend struct cs_state;
    friend struct cs_shared_state;

    cs_float get_val_min() const;
    cs_float get_val_max() const;

    cs_float get_value() const;
    void set_value(cs_float val);

private:
    cs_fvar(
        cs_strref n, cs_float m, cs_float x, cs_float v,
        cs_var_cb f, int flags
    );

    cs_float p_storage, p_minval, p_maxval, p_overrideval;
};

struct LIBCUBESCRIPT_EXPORT cs_svar: cs_var {
    friend struct cs_state;
    friend struct cs_shared_state;

    cs_strref get_value() const;
    void set_value(cs_strref val);

private:
    cs_svar(cs_strref n, cs_strref v, cs_strref ov, cs_var_cb f, int flags);

    cs_strref p_storage, p_overrideval;
};

struct LIBCUBESCRIPT_EXPORT cs_alias: cs_ident {
    friend struct cs_state;
    friend struct cs_shared_state;
    friend struct cs_alias_internal;

    cs_value get_value() const {
        return p_val;
    }

    void get_cval(cs_value &v) const;
private:
    cs_alias(cs_state &cs, cs_strref n, cs_strref a, int flags);
    cs_alias(cs_state &cs, cs_strref n, std::string_view a, int flags);
    cs_alias(cs_state &cs, cs_strref n, cs_int a, int flags);
    cs_alias(cs_state &cs, cs_strref n, cs_float a, int flags);
    cs_alias(cs_state &cs, cs_strref n, int flags);
    cs_alias(cs_state &cs, cs_strref n, cs_value v, int flags);

    cs_bcode *p_acode;
    cs_ident_stack *p_astack;
    cs_value p_val;
};

struct cs_command: cs_ident {
    friend struct cs_state;
    friend struct cs_shared_state;
    friend struct cs_cmd_internal;

    std::string_view get_args() const;
    int get_num_args() const;

private:
    cs_command(cs_strref name, cs_strref args, int numargs, cs_command_cb func);

    cs_strref p_cargs;
    cs_command_cb p_cb_cftv;
    int p_numargs;
};

struct cs_ident_link;

enum {
    CS_LIB_MATH   = 1 << 0,
    CS_LIB_STRING = 1 << 1,
    CS_LIB_LIST   = 1 << 2,
    CS_LIB_ALL    = 0b111
};

enum class cs_loop_state {
    NORMAL = 0, BREAK, CONTINUE
};

static inline void *cs_default_alloc(void *, void *p, size_t, size_t ns) {
    if (!ns) {
        delete[] static_cast<unsigned char *>(p);
        return nullptr;
    }
    return new unsigned char[ns];
}

struct LIBCUBESCRIPT_EXPORT cs_state {
    friend struct cs_error;
    friend struct cs_strman;
    friend struct cs_strref;
    friend struct cs_value;
    friend struct cs_gen_state;
    friend inline cs_shared_state *cs_get_sstate(cs_state &);

    cs_shared_state *p_state;
    cs_ident_link *p_callstack = nullptr;

    int identflags = 0;

    cs_state(cs_alloc_cb func = cs_default_alloc, void *data = nullptr);
    virtual ~cs_state();

    cs_state(cs_state const &) = delete;
    cs_state(cs_state &&s) {
        swap(s);
    }

    cs_state &operator=(cs_state const &) = delete;
    cs_state &operator=(cs_state &&s) {
        swap(s);
        s.destroy();
        return *this;
    }

    void destroy();

    void swap(cs_state &s) {
        std::swap(p_state, s.p_state);
        std::swap(p_callstack, s.p_callstack);
        std::swap(identflags, s.identflags);
        std::swap(p_pstate, s.p_pstate);
        std::swap(p_inloop, s.p_inloop);
        std::swap(p_owner, s.p_owner);
        std::swap(p_callhook, s.p_callhook);
    }

    cs_state new_thread();

    cs_hook_cb set_call_hook(cs_hook_cb func);
    cs_hook_cb const &get_call_hook() const;
    cs_hook_cb &get_call_hook();

    cs_vprint_cb set_var_printer(cs_vprint_cb func);
    cs_vprint_cb const &get_var_printer() const;

    void init_libs(int libs = CS_LIB_ALL);

    void clear_override(cs_ident &id);
    void clear_overrides();

    cs_ident *new_ident(std::string_view name, int flags = CS_IDF_UNKNOWN);
    cs_ident *force_ident(cs_value &v);

    cs_ivar *new_ivar(
        std::string_view n, cs_int m, cs_int x, cs_int v,
        cs_var_cb f = cs_var_cb(), int flags = 0
    );
    cs_fvar *new_fvar(
        std::string_view n, cs_float m, cs_float x, cs_float v,
        cs_var_cb f = cs_var_cb(), int flags = 0
    );
    cs_svar *new_svar(
        std::string_view n, std::string_view v,
        cs_var_cb f = cs_var_cb(), int flags = 0
    );

    cs_command *new_command(
        std::string_view name, std::string_view args, cs_command_cb func
    );

    cs_ident *get_ident(std::string_view name);
    cs_alias *get_alias(std::string_view name);
    bool have_ident(std::string_view name);

    std::span<cs_ident *> get_idents();
    std::span<cs_ident const *> get_idents() const;

    void reset_var(std::string_view name);
    void touch_var(std::string_view name);

    void run(cs_bcode *code, cs_value &ret);
    void run(std::string_view code, cs_value &ret);
    void run(std::string_view code, cs_value &ret, std::string_view source);
    void run(cs_ident *id, std::span<cs_value> args, cs_value &ret);

    cs_value run(cs_bcode *code);
    cs_value run(std::string_view code);
    cs_value run(std::string_view code, std::string_view source);
    cs_value run(cs_ident *id, std::span<cs_value> args);

    cs_loop_state run_loop(cs_bcode *code, cs_value &ret);
    cs_loop_state run_loop(cs_bcode *code);

    bool is_in_loop() const {
        return p_inloop;
    }

    void set_alias(std::string_view name, cs_value v);

    void set_var_int(
        std::string_view name, cs_int v,
        bool dofunc = true, bool doclamp = true
    );
    void set_var_float(
        std::string_view name, cs_float v,
        bool dofunc  = true, bool doclamp = true
    );
    void set_var_str(
        std::string_view name, std::string_view v, bool dofunc = true
    );

    void set_var_int_checked(cs_ivar *iv, cs_int v);
    void set_var_int_checked(cs_ivar *iv, std::span<cs_value> args);
    void set_var_float_checked(cs_fvar *fv, cs_float v);
    void set_var_str_checked(cs_svar *fv, std::string_view v);

    std::optional<cs_int> get_var_int(std::string_view name);
    std::optional<cs_float> get_var_float(std::string_view name);
    std::optional<cs_strref> get_var_str(std::string_view name);

    std::optional<cs_int> get_var_min_int(std::string_view name);
    std::optional<cs_int> get_var_max_int(std::string_view name);

    std::optional<cs_float> get_var_min_float(std::string_view name);
    std::optional<cs_float> get_var_max_float(std::string_view name);

    std::optional<cs_strref> get_alias_val(std::string_view name);

    void print_var(cs_var const &v) const;

private:
    LIBCUBESCRIPT_LOCAL cs_state(cs_shared_state *s);

    cs_ident *add_ident(cs_ident *id);

    LIBCUBESCRIPT_LOCAL void *alloc(void *ptr, size_t olds, size_t news);

    cs_gen_state *p_pstate = nullptr;
    int p_inloop = 0;
    bool p_owner = false;

    char p_errbuf[512];

    cs_hook_cb p_callhook;
};

struct cs_stack_state_node {
    cs_stack_state_node const *next;
    cs_ident const *id;
    int index;
};

struct cs_stack_state {
    cs_stack_state() = delete;
    cs_stack_state(cs_state &cs, cs_stack_state_node *nd = nullptr, bool gap = false);
    cs_stack_state(cs_stack_state const &) = delete;
    cs_stack_state(cs_stack_state &&st);
    ~cs_stack_state();

    cs_stack_state &operator=(cs_stack_state const &) = delete;
    cs_stack_state &operator=(cs_stack_state &&);

    cs_stack_state_node const *get() const;
    bool gap() const;

private:
    cs_state &p_state;
    cs_stack_state_node *p_node;
    bool p_gap;
};

struct cs_error {
    friend struct cs_state;

    cs_error() = delete;
    cs_error(cs_error const &) = delete;
    cs_error(cs_error &&v):
        p_errmsg(v.p_errmsg), p_stack(std::move(v.p_stack))
    {}

    std::string_view what() const {
        return p_errmsg;
    }

    cs_stack_state &get_stack() {
        return p_stack;
    }

    cs_stack_state const &get_stack() const {
        return p_stack;
    }

    cs_error(cs_state &cs, std::string_view msg):
        p_errmsg(), p_stack(cs)
    {
        p_errmsg = save_msg(cs, msg);
        p_stack = save_stack(cs);
    }

    template<typename ...A>
    cs_error(cs_state &cs, std::string_view msg, A const &...args):
        p_errmsg(), p_stack(cs)
    {
        char fbuf[512];
        int written = std::snprintf(
            fbuf, sizeof(fbuf), msg.data(), args...
        );
        if (written >= int(sizeof(fbuf))) {
            written = std::strlen(fbuf);
        } else if (written <= 0) {
            std::strncpy(fbuf, "format error", sizeof(fbuf));
            written = std::strlen(fbuf);
        }
        p_errmsg = save_msg(cs, std::string_view{
            static_cast<char const *>(fbuf),
            std::size_t(written)
        });
        p_stack = save_stack(cs);
    }

private:
    cs_stack_state save_stack(cs_state &cs);
    std::string_view save_msg(cs_state &cs, std::string_view v);

    std::string_view p_errmsg;
    cs_stack_state p_stack;
};

struct LIBCUBESCRIPT_EXPORT cs_stacked_value: cs_value {
    cs_stacked_value(cs_state &cs, cs_ident *id = nullptr);
    ~cs_stacked_value();

    cs_stacked_value(cs_stacked_value const &) = delete;
    cs_stacked_value(cs_stacked_value &&) = delete;

    cs_stacked_value &operator=(cs_stacked_value const &) = delete;
    cs_stacked_value &operator=(cs_stacked_value &&v) = delete;

    cs_stacked_value &operator=(cs_value const &v);
    cs_stacked_value &operator=(cs_value &&v);

    bool set_alias(cs_ident *id);
    cs_alias *get_alias() const;
    bool has_alias() const;

    bool push();
    bool pop();

private:
    cs_alias *p_a;
    cs_ident_stack p_stack;
    bool p_pushed;
};

struct LIBCUBESCRIPT_EXPORT cs_list_parse_state {
    cs_list_parse_state(std::string_view s = std::string_view{}):
        input_beg{s.data()}, input_end{s.data() + s.size()}
     {}

    void set_input(std::string_view s) {
        input_beg = s.data();
        input_end = s.data() + s.size();
    }

    std::string_view get_input() const {
        return std::string_view{input_beg, std::size_t(input_end - input_beg)};
    }

    char const *input_beg, *input_end;
    std::string_view item{};
    std::string_view quoted_item{};
};

LIBCUBESCRIPT_EXPORT bool list_parse(cs_list_parse_state &ps, cs_state &cs);
LIBCUBESCRIPT_EXPORT std::size_t list_count(cs_list_parse_state &ps, cs_state &cs);
LIBCUBESCRIPT_EXPORT cs_strref list_get_item(cs_list_parse_state &ps, cs_state &cs);
LIBCUBESCRIPT_EXPORT void list_find_item(cs_list_parse_state &ps);

LIBCUBESCRIPT_EXPORT cs_strref value_list_concat(
    cs_state &cs, std::span<cs_value> vals,
    std::string_view sep = std::string_view{}
);

namespace util {
    template<typename R>
    inline R escape_string(R writer, std::string_view str) {
        *writer++ = '"';
        for (auto c: str) {
            switch (c) {
                case '\n': *writer++ = '^'; *writer++ = 'n'; break;
                case '\t': *writer++ = '^'; *writer++ = 't'; break;
                case '\f': *writer++ = '^'; *writer++ = 'f'; break;
                case  '"': *writer++ = '^'; *writer++ = '"'; break;
                case  '^': *writer++ = '^'; *writer++ = '^'; break;
                default: *writer++ = c; break;
            }
        }
        *writer++ = '"';
        return writer;
    }

    template<typename R>
    inline R  unescape_string(R writer, std::string_view str) {
        for (auto it = str.begin(); it != str.end(); ++it) {
            if (*it == '^') {
                ++it;
                if (it == str.end()) {
                    break;
                }
                switch (*it) {
                    case 'n': *writer++ = '\n'; break;
                    case 't': *writer++ = '\r'; break;
                    case 'f': *writer++ = '\f'; break;
                    case '"': *writer++ = '"'; break;
                    case '^': *writer++ = '^'; break;
                    default: *writer++ = *it; break;
                }
            } else if (*it == '\\') {
                ++it;
                if (it == str.end()) {
                    break;
                }
                char c = *it;
                if ((c == '\r') || (c == '\n')) {
                    if ((c == '\r') && ((it + 1) != str.end())) {
                        if (it[1] == '\n') {
                            ++it;
                        }
                    }
                    continue;
                }
                *writer++ = '\\';
            } else {
                *writer++ = *it;
            }
        }
        return writer;
    }

    LIBCUBESCRIPT_EXPORT char const *parse_string(
        cs_state &cs, std::string_view str, size_t &nlines
    );

    inline char const *parse_string(
        cs_state &cs, std::string_view str
    ) {
        size_t nlines;
        return parse_string(cs, str, nlines);
    }

    LIBCUBESCRIPT_EXPORT char const *parse_word(cs_state &cs, std::string_view str);

    template<typename R>
    inline R print_stack(R writer, cs_stack_state const &st) {
        char buf[32] = {0};
        auto nd = st.get();
        while (nd) {
            auto name = nd->id->get_name();
            *writer++ = ' ';
            *writer++ = ' ';
            if ((nd->index == 1) && st.gap()) {
                *writer++ = '.';
                *writer++ = '.';
            }
            snprintf(buf, sizeof(buf), "%d", nd->index);
            char const *p = buf;
            std::copy(p, p + strlen(p), writer);
            *writer++ = ')';
            std::copy(name.begin(), name.end(), writer);
            nd = nd->next;
            if (nd) {
                *writer++ = '\n';
            }
        }
        return writer;
    }
} /* namespace util */

} /* namespace cscript */

#endif /* LIBCUBESCRIPT_CUBESCRIPT_HH */