/*
 * Copyright (C) 2012, 2013
 *     Dale Weiler
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <string.h>
#include "parser.h"

/*
 * Provides all the "intrinsics" / "builtins" for GMQCC. These can do
 * a few things, they can provide fall back implementations for math
 * functions if the definitions don't exist for some given engine. Or
 * then can determine definitions for existing builtins, and simply
 * wrap back to them instead.  This is like a "portable" intrface that
 * is entered when -fintrin is used (causing all existing builtins to
 * be ignored by the compiler and instead interface through here.
 */
#define INTRIN_VAL(VALUE, NAME, FUNC, STYPE, VTYPE)                    \
    do {                                                               \
        (VALUE) = ast_value_new (                                      \
            parser_ctx(intrin->parser),                                \
            "__builtin_" NAME,                                         \
            TYPE_FUNCTION                                              \
        );                                                             \
        (VALUE)->intrinsic = true;                                     \
        (VALUE)->expression.next = (ast_expression*)ast_value_new (    \
            parser_ctx(intrin->parser),                                \
            STYPE,                                                     \
            VTYPE                                                      \
        );                                                             \
        (FUNC) = ast_function_new (                                    \
            parser_ctx(intrin->parser),                                \
            "__builtin_" NAME,                                         \
            (VALUE)                                                    \
        );                                                             \
        (VALUE)->expression.flags |= AST_FLAG_ERASEABLE;               \
    } while (0)

#define INTRIN_REG(FUNC, VALUE)                                        \
    do {                                                               \
        vec_push(intrin->parser->functions, (FUNC));                   \
        vec_push(intrin->parser->globals,   (ast_expression*)(VALUE)); \
    } while (0)

#define QC_M_E 2.71828182845905f

static ast_expression *intrin_pow (intrin_t *intrin) {
    /*
     * float pow(float x, float y) {
     *   float local = 1.0f;
     *   while (y > 0) {
     *     while (!(y & 1)) {
     *       y >>= 2;
     *       x *=  x;
     *     }
     *     y--;
     *     local *= x;
     *   }
     *   return local;
     * }
     */
    static ast_value *value = NULL;

    if (!value) {
        ast_value    *arg1  = ast_value_new(parser_ctx(intrin->parser), "x",     TYPE_FLOAT);
        ast_value    *arg2  = ast_value_new(parser_ctx(intrin->parser), "y",     TYPE_FLOAT);
        ast_value    *local = ast_value_new(parser_ctx(intrin->parser), "local", TYPE_FLOAT);
        ast_block    *body  = ast_block_new(parser_ctx(intrin->parser));
        ast_block    *l1b   = ast_block_new(parser_ctx(intrin->parser)); /* loop 1 body */
        ast_block    *l2b   = ast_block_new(parser_ctx(intrin->parser)); /* loop 2 body */
        ast_loop     *loop1 = NULL;
        ast_loop     *loop2 = NULL;
        ast_function *func  = NULL;

        INTRIN_VAL(value, "pow", func, "<float>", TYPE_FLOAT);

        /* arguments */
        vec_push(value->expression.params, arg1);
        vec_push(value->expression.params, arg2);

        /* local */
        vec_push(body->locals, local);

        /* assignment to local of value 1.0f */
        vec_push(body->exprs,
            (ast_expression*)ast_store_new (
                parser_ctx(intrin->parser),
                INSTR_STORE_F,
                (ast_expression*)local,
                (ast_expression*)intrin->fold->imm_float[1] /* 1 == 1.0f */
            )
        );

        /* y >>= 2 */
        vec_push(l2b->exprs,
            (ast_expression*)ast_binstore_new (
                parser_ctx(intrin->parser),
                INSTR_STORE_F,
                INSTR_MUL_F,
                (ast_expression*)arg2,
                (ast_expression*)fold_constgen_float(intrin->parser->fold, 0.25f)
            )
        );

        /* x *= x */
        vec_push(l2b->exprs,
            (ast_expression*)ast_binstore_new (
                parser_ctx(intrin->parser),
                INSTR_STORE_F,
                INSTR_MUL_F,
                (ast_expression*)arg1,
                (ast_expression*)arg1
            )
        );

        /* while (!(y&1)) */
        loop2 = ast_loop_new (
            parser_ctx(intrin->parser),
            NULL,
            (ast_expression*)ast_binary_new (
                parser_ctx(intrin->parser),
                INSTR_AND,
                (ast_expression*)arg2,
                (ast_expression*)intrin->fold->imm_float[1] /* 1 == 1.0f */
            ),
            true, /* ! not */
            NULL,
            false,
            NULL,
            (ast_expression*)l2b
        );

        /* push nested loop into loop expressions */
        vec_push(l1b->exprs, (ast_expression*)loop2);

        /* y-- */
        vec_push(l1b->exprs,
            (ast_expression*)ast_binstore_new (
                parser_ctx(intrin->parser),
                INSTR_STORE_F,
                INSTR_SUB_F,
                (ast_expression*)arg2,
                (ast_expression*)intrin->fold->imm_float[1] /* 1 == 1.0f */
            )
        );
        /* local *= x */
        vec_push(l1b->exprs,
            (ast_expression*)ast_binstore_new (
                parser_ctx(intrin->parser),
                INSTR_STORE_F,
                INSTR_MUL_F,
                (ast_expression*)local,
                (ast_expression*)arg1
            )
        );

        /* while (y > 0) */
        loop1 = ast_loop_new (
            parser_ctx(intrin->parser),
            NULL,
            (ast_expression*)ast_binary_new (
                parser_ctx(intrin->parser),
                INSTR_GT,
                (ast_expression*)arg2,
                (ast_expression*)intrin->fold->imm_float[0] /* 0 == 0.0f */
            ),
            false,
            NULL,
            false,
            NULL,
            (ast_expression*)l1b
        );

        /* push the loop1 into the body for the function */
        vec_push(body->exprs, (ast_expression*)loop1);

        /* return local; */
        vec_push(body->exprs,
            (ast_expression*)ast_return_new (
                parser_ctx(intrin->parser),
                (ast_expression*)local
            )
        );

        /* push block and register intrin for codegen */
        vec_push(func->blocks, body);

        INTRIN_REG(func, value);
    }

    return (ast_expression*)value;
}

static ast_expression *intrin_mod(intrin_t *intrin) {
    /*
     * float mod(float x, float y) {
     *   return x - y * floor(x / y);
     * }
     */
    static ast_value *value = NULL;

    if (!value) {
        ast_call     *call  = ast_call_new (parser_ctx(intrin->parser), intrin_func(intrin, "floor"));
        ast_value    *arg1  = ast_value_new(parser_ctx(intrin->parser), "x", TYPE_FLOAT);
        ast_value    *arg2  = ast_value_new(parser_ctx(intrin->parser), "y", TYPE_FLOAT);
        ast_block    *body  = ast_block_new(parser_ctx(intrin->parser));
        ast_function *func  = NULL;

        INTRIN_VAL(value, "mod", func, "<float>", TYPE_FLOAT);

        /* floor(x/y) */
        vec_push(call->params,
            (ast_expression*)ast_binary_new (
                parser_ctx(intrin->parser),
                INSTR_DIV_F,
                (ast_expression*)arg1,
                (ast_expression*)arg2
            )
        );

        vec_push(body->exprs,
            (ast_expression*)ast_return_new(
                parser_ctx(intrin->parser),
                (ast_expression*)ast_binary_new(
                    parser_ctx(intrin->parser),
                    INSTR_SUB_F,
                    (ast_expression*)arg1,
                    (ast_expression*)ast_binary_new(
                        parser_ctx(intrin->parser),
                        INSTR_MUL_F,
                        (ast_expression*)arg2,
                        (ast_expression*)call
                    )
                )
            )
        );

        vec_push(value->expression.params, arg1); /* float x (for param) */
        vec_push(value->expression.params, arg2); /* float y (for param) */

        vec_push(func->blocks,             body); /* {{{ body }}} */

        INTRIN_REG(func, value);
    }

    return (ast_expression*)value;
}

static ast_expression *intrin_exp(intrin_t *intrin) {
    /*
     * float exp(float x) {
     *     return pow(QC_M_E, x);
     * }
     */
    static ast_value *value = NULL;

    if (!value) {
        ast_call     *call = ast_call_new (parser_ctx(intrin->parser), intrin_func(intrin, "pow"));
        ast_value    *arg1 = ast_value_new(parser_ctx(intrin->parser), "x", TYPE_FLOAT);
        ast_block    *body = ast_block_new(parser_ctx(intrin->parser));
        ast_function *func = NULL;

        INTRIN_VAL(value, "exp", func, "<float>", TYPE_FLOAT);

        /* push arguments for params to call */
        vec_push(call->params, (ast_expression*)fold_constgen_float(intrin->fold, QC_M_E));
        vec_push(call->params, (ast_expression*)arg1);

        /* return pow(QC_M_E, x) */
        vec_push(body->exprs,
            (ast_expression*)ast_return_new(
                parser_ctx(intrin->parser),
                (ast_expression*)call
            )
        );

        vec_push(value->expression.params, arg1); /* float x (for param) */

        vec_push(func->blocks,             body); /* {{{ body }}} */

        INTRIN_REG(func, value);
    }

    return (ast_expression*)value;
}

static ast_expression *intrin_isnan(intrin_t *intrin) {
    /*
     * float isnan(float x) {
     *   float local;
     *   local = x;
     *
     *   return (x != local);
     * }
     */
    static ast_value *value = NULL;

    if (!value) {
        ast_value    *arg1   = ast_value_new(parser_ctx(intrin->parser), "x",     TYPE_FLOAT);
        ast_value    *local  = ast_value_new(parser_ctx(intrin->parser), "local", TYPE_FLOAT);
        ast_block    *body   = ast_block_new(parser_ctx(intrin->parser));
        ast_function *func   = NULL;

        INTRIN_VAL(value, "isnan", func, "<float>", TYPE_FLOAT);

        vec_push(body->locals, local);
        vec_push(body->exprs,
            (ast_expression*)ast_store_new(
                parser_ctx(intrin->parser),
                INSTR_STORE_F,
                (ast_expression*)local,
                (ast_expression*)arg1
            )
        );

        vec_push(body->exprs,
            (ast_expression*)ast_return_new(
                parser_ctx(intrin->parser),
                (ast_expression*)ast_binary_new(
                    parser_ctx(intrin->parser),
                    INSTR_NE_F,
                    (ast_expression*)arg1,
                    (ast_expression*)local
                )
            )
        );

        vec_push(value->expression.params, arg1);
        vec_push(func->blocks, body);

        INTRIN_REG(func, value);
    }

    return (ast_expression*)value;
}

static ast_expression *intrin_fabs(intrin_t *intrin) {
    /*
     * float fabs(float x) {
     *     return x < 0 ? -x : x;
     * }
     */
    static ast_value *value = NULL;
    if (!value) {
        ast_value    *arg1   = ast_value_new(parser_ctx(intrin->parser), "x",     TYPE_FLOAT);
        ast_block    *body   = ast_block_new(parser_ctx(intrin->parser));
        ast_function *func   = NULL;

        INTRIN_VAL(value, "fabs", func, "<float>", TYPE_FLOAT);

        vec_push(body->exprs,
            (ast_expression*)ast_return_new(
                parser_ctx(intrin->parser),
                (ast_expression*)ast_ternary_new(
                    parser_ctx(intrin->parser),
                    (ast_expression*)ast_binary_new(
                        parser_ctx(intrin->parser),
                        INSTR_LE,
                        (ast_expression*)arg1,
                        (ast_expression*)intrin->fold->imm_float[0]
                    ),
                    (ast_expression*)ast_binary_new(
                        parser_ctx(intrin->parser),
                        INSTR_SUB_F,
                        (ast_expression*)intrin->fold->imm_float[0],
                        (ast_expression*)arg1
                    ),
                    (ast_expression*)arg1
                )
            )
        );

        vec_push(value->expression.params, arg1);
        vec_push(func->blocks, body);

        INTRIN_REG(func, value);
    }

    return (ast_expression*)value;
}

#undef INTRIN_REG
#undef INTRIN_VAL

/*
 * TODO: make static (and handle ast_type_string) here for the builtin
 * instead of in SYA parse close.
 */
ast_expression *intrin_debug_typestring(intrin_t *intrin) {
    (void)intrin;
    return (ast_expression*)0x1;
}

static const intrin_func_t intrinsics[] = {
    {&intrin_exp,              "__builtin_exp",              "exp"},
    {&intrin_mod,              "__builtin_mod",              "mod"},
    {&intrin_pow,              "__builtin_pow",              "pow"},
    {&intrin_isnan,            "__builtin_isnan",            "isnan"},
    {&intrin_fabs,             "__builtin_fabs",             "fabs"},
    {&intrin_debug_typestring, "__builtin_debug_typestring", ""}
};

static void intrin_error(intrin_t *intrin, const char *fmt, ...) {
    va_list ap;
    va_start(ap, fmt);
    vcompile_error(intrin->parser->lex->tok.ctx, fmt, ap);
    va_end(ap);
}

/* exposed */
intrin_t *intrin_init(parser_t *parser) {
    intrin_t *intrin = (intrin_t*)mem_a(sizeof(intrin_t));
    intrin->parser     = parser;
    intrin->fold       = parser->fold;
    intrin->intrinsics = NULL;

    vec_append(intrin->intrinsics, sizeof(intrinsics)/sizeof(*intrinsics), intrinsics);

    return intrin;
}

void intrin_cleanup(intrin_t *intrin) {
    vec_free(intrin->intrinsics);
    mem_d(intrin);
}

ast_expression *intrin_fold(intrin_t *intrin, ast_value *value, ast_expression **exprs) {
    size_t i;

    if (!value || !value->name)
        return NULL;

    for (i = 0; i < vec_size(intrin->intrinsics); i++)
        if (!strcmp(value->name, intrin->intrinsics[i].name))
            return fold_intrin(intrin->fold, value->name, exprs);

    return NULL;
}

ast_expression *intrin_func(intrin_t *intrin, const char *name) {
    size_t       i    = 0;
    void        *find;

    /* try current first */
    if ((find = (void*)parser_find_global(intrin->parser, name)) && ((ast_value*)find)->expression.vtype == TYPE_FUNCTION)
        for (i = 0; i < vec_size(intrin->parser->functions); ++i)
            if (((ast_value*)find)->name && !strcmp(intrin->parser->functions[i]->name, ((ast_value*)find)->name) && intrin->parser->functions[i]->builtin < 0)
                return (ast_expression*)find;
    /* try name second */
    for (i = 0; i < vec_size(intrin->intrinsics); i++)
        if (!strcmp(intrin->intrinsics[i].name, name))
            return intrin->intrinsics[i].intrin(intrin);
    /* try alias third */
    for (i = 0; i < vec_size(intrin->intrinsics); i++)
        if (!strcmp(intrin->intrinsics[i].alias, name))
            return intrin->intrinsics[i].intrin(intrin);

    intrin_error(intrin, "need function: `%s` compiler depends on it", name);
    return NULL;
}