#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>
#include <string.h>
#include <assert.h>

#include "oberon.h"
#include "generator.h"

#include <libgccjit.h>

/*
 * oberon_var_t -> gvar == gcc_jit_lvalue;
 * oberon_type_t -> gtype == gcc_jit_type;
 * oberon_context_t -> gctx == gen_context_t;
 */ 

typedef struct
{
	gcc_jit_context * gcc_context;
	gcc_jit_block * gcc_block;
	gcc_jit_result * gcc_result;
} gen_context_t;

static void printcontext(oberon_context_t * ctx, char * s)
{
/*
	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;
	gcc_jit_block * gcc_block = gen_context -> gcc_block;

	printf("%s:\n", s);
	printf("  ctx     = %p:\n", ctx);
	printf("  gctx    = %p:\n", gctx);
	printf("  context = %p:\n", context);
	printf("  block   = %p:\n", block);
*/
}

// =======================================================================
//   ALLOC
// ======================================================================= 

void
oberon_generator_init_context(oberon_context_t * ctx)
{
	gen_context_t * gen_context = malloc(sizeof *gen_context);
	memset(gen_context, 0, sizeof *gen_context);

	gcc_jit_context * gcc_context;
	gcc_context = gcc_jit_context_acquire();

	ctx -> gen_context = gen_context;
	gen_context -> gcc_context = gcc_context;

	printcontext(ctx, "oberon_generator_init_context");
}

void
oberon_generator_destroy_context(oberon_context_t * ctx)
{
	printcontext(ctx, "oberon_generator_destroy_context");

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;

	gcc_jit_context_release(gcc_context);
}

void
oberon_generator_init_type(oberon_context_t * ctx, oberon_type_t * type)
{
	printcontext(ctx, "oberon_generator_init_type");

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;

	gcc_jit_type * gen_type;
	if(type -> class == OBERON_TYPE_INTEGER)
	{
		gen_type = gcc_jit_context_get_int_type(gcc_context, type -> size, 1);
	}
	else if(type -> class == OBERON_TYPE_BOOLEAN)
	{
		gen_type = gcc_jit_context_get_type(gcc_context, GCC_JIT_TYPE_BOOL);
	}
	else
	{
		oberon_error(ctx, "oberon_generator_init_type: invalid type class %i", type -> class);
	}

	type -> gen_type = gen_type;
}

void
oberon_generator_init_var(oberon_context_t * ctx, oberon_var_t * var)
{
	printcontext(ctx, "oberon_generator_init_var");

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;
	gcc_jit_type * gen_type = var -> type -> gen_type;
	const char * name = var -> name;

	gcc_jit_lvalue * gen_var;
	gen_var = gcc_jit_context_new_global(gcc_context, NULL, GCC_JIT_GLOBAL_INTERNAL, gen_type, name);

	var -> gen_var = gen_var;
}

// =======================================================================
//   GENERATOR
// ======================================================================= 

void
oberon_generate_begin_module(oberon_context_t * ctx)
{
	printcontext(ctx, "oberon_generate_begin_module");

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;

	gcc_jit_type * void_type = gcc_jit_context_get_type(gcc_context, GCC_JIT_TYPE_VOID);
	gcc_jit_function * func = gcc_jit_context_new_function(
		gcc_context, NULL, GCC_JIT_FUNCTION_EXPORTED, void_type, "BEGIN", 0, NULL, 0
	);
	gcc_jit_block * gcc_block = gcc_jit_function_new_block(func, NULL);

	gen_context -> gcc_block = gcc_block;
}

void
oberon_generate_end_module(oberon_context_t * ctx)
{
	printcontext(ctx, "oberon_generate_end_module");

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_block * gcc_block = gen_context -> gcc_block;

	gcc_jit_block_end_with_void_return(gcc_block, NULL);

	gen_context -> gcc_block = NULL;
}

static gcc_jit_lvalue *
lvalue_from_expr(oberon_context_t *ctx, oberon_expr_t * expr)
{
	gcc_jit_lvalue * left;
	oberon_item_t * item;

	if(expr -> is_item)
	{
		item = (oberon_item_t *) expr;
		if(item -> mode != MODE_VAR)
		{
			oberon_error(ctx, "invalid lvalue expression");
		}
		left = item -> var -> gen_var;
	}
	else
	{
		oberon_error(ctx, "invalid lvalue expression");
	}

	return left;
}

static gcc_jit_rvalue * rvalue_from_expr(oberon_context_t * ctx, oberon_expr_t * expr);

static gcc_jit_rvalue *
rvalue_from_item(oberon_context_t * ctx, oberon_item_t * item)
{
	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;

	gcc_jit_rvalue * right;
	if(item -> mode == MODE_VAR)
	{
		gcc_jit_lvalue * gen_var = item -> var -> gen_var;
		right = gcc_jit_lvalue_as_rvalue(gen_var);
	}
	else if(item -> mode == MODE_INTEGER)
	{
		gcc_jit_type * int_type = gcc_jit_context_get_type(gcc_context, GCC_JIT_TYPE_INT);
		right = gcc_jit_context_new_rvalue_from_int(gcc_context, int_type, item -> integer);
	}
	else if(item -> mode == MODE_BOOLEAN)
	{
		gcc_jit_type * bool_type = gcc_jit_context_get_type(gcc_context, GCC_JIT_TYPE_BOOL);
		if(item -> boolean)
		{
			right = gcc_jit_context_one(gcc_context, bool_type);
		}
		else
		{
			right = gcc_jit_context_zero(gcc_context, bool_type);			
		}
	}
	else
	{
		oberon_error(ctx, "oberon_generate_push: invalid mode %i", item -> mode);
	}

	return right;
}

struct {
	int type; // 0 - unary, 1 - binary, 2 - comp
	union {
		enum gcc_jit_unary_op unary_op;
		enum gcc_jit_binary_op binary_op;
		enum gcc_jit_comparison comp_op;
	};
} op_table[] = {
	{ 0, .unary_op = GCC_JIT_UNARY_OP_LOGICAL_NEGATE },
	{ 0, .unary_op = GCC_JIT_UNARY_OP_MINUS },

	{ 1, .binary_op = GCC_JIT_BINARY_OP_PLUS },
	{ 1, .binary_op = GCC_JIT_BINARY_OP_MINUS },
	{ 1, .binary_op = GCC_JIT_BINARY_OP_DIVIDE },
	{ 1, .binary_op = GCC_JIT_BINARY_OP_MODULO },
	{ 1, .binary_op = GCC_JIT_BINARY_OP_LOGICAL_AND },
	{ 1, .binary_op = GCC_JIT_BINARY_OP_LOGICAL_OR },

	{ 2, .comp_op = GCC_JIT_COMPARISON_EQ },
	{ 2, .comp_op = GCC_JIT_COMPARISON_NE },
	{ 2, .comp_op = GCC_JIT_COMPARISON_LT },
	{ 2, .comp_op = GCC_JIT_COMPARISON_LE },
	{ 2, .comp_op = GCC_JIT_COMPARISON_GT },
	{ 2, .comp_op = GCC_JIT_COMPARISON_GE }
};

static gcc_jit_rvalue *
rvalue_from_operator(oberon_context_t * ctx, oberon_oper_t * operator)
{
	gcc_jit_rvalue * right;

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;
	gcc_jit_type * result_type = operator -> result -> gen_type;

	int expr_type = op_table[operator -> op].type;
	if(expr_type == 0)
	{
		enum gcc_jit_unary_op op = op_table[operator -> op].unary_op;
		gcc_jit_rvalue * l = rvalue_from_expr(ctx, operator -> left);
		right = gcc_jit_context_new_unary_op(gcc_context, NULL, op, result_type, l);
	}
	else if(expr_type == 1)
	{
		enum gcc_jit_unary_op op = op_table[operator -> op].binary_op;
		gcc_jit_rvalue * l = rvalue_from_expr(ctx, operator -> left);
		gcc_jit_rvalue * r = rvalue_from_expr(ctx, operator -> right);
		right = gcc_jit_context_new_binary_op(gcc_context, NULL, op, result_type, l, r);
	}
	else if(expr_type == 2)
	{
		enum gcc_jit_comparison op = op_table[operator -> op].comp_op;
		gcc_jit_rvalue * l = rvalue_from_expr(ctx, operator -> left);
                gcc_jit_rvalue * r = rvalue_from_expr(ctx, operator -> right);
		right = gcc_jit_context_new_comparison(gcc_context, NULL, op, l, r);
	}
	else
	{
		oberon_error(ctx, "rvalue_from_operator: wat");
	}

	return right;
}

static gcc_jit_rvalue *
rvalue_from_expr(oberon_context_t * ctx, oberon_expr_t * expr)
{
	gcc_jit_rvalue * right;

	if(expr -> is_item)
	{
		oberon_item_t * item = (oberon_item_t *) expr;
		right = rvalue_from_item(ctx, item);
	}
	else
	{
		oberon_oper_t * operator = (oberon_oper_t *) expr;
		right = rvalue_from_operator(ctx, operator);
	}

	return right;
}

void
oberon_generate_assign(oberon_context_t * ctx, oberon_expr_t * src, oberon_expr_t * dst)
{
	gcc_jit_lvalue * left;
	left = lvalue_from_expr(ctx, dst);

	gcc_jit_rvalue * right;
	right = rvalue_from_expr(ctx, src);

	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_block * gcc_block = gen_context -> gcc_block;
	gcc_jit_block_add_assignment(gcc_block, NULL, left, right);
}

void
oberon_generate_code(oberon_context_t * ctx)
{
	gen_context_t * gen_context = ctx -> gen_context;
	gcc_jit_context * gcc_context = gen_context -> gcc_context;

	gcc_jit_result * gcc_result;
	gcc_result = gcc_jit_context_compile(gcc_context);

	gen_context -> gcc_result = gcc_result;
	ctx -> mod -> begin = gcc_jit_result_get_code(gcc_result, "BEGIN");
}