#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "func.h"
#include "ir.h"
#include "node.h"
#include "ply.h"
#include "sym.h"
#include "type.h"

struct providers {
	struct provider **ps;
	size_t len;
} providers;

#define providers_foreach(_ps, _p) \
	for((_p) = (_ps)->ps; (_p) < &(_ps)->ps[(_ps)->len]; (_p)++)

struct provider *provider_get(const char *name)
{
	struct provider **p;

	providers_foreach(&providers, p) {
		if (strstr((*p)->name, name) == (*p)->name)
			return *p;
	}

	return NULL;
}

void provider_register(struct provider *p)
{
	assert(p);
	assert(p->probe);
	assert(p->sym_alloc);

	providers.ps = realloc(providers.ps,
				 ++providers.len * sizeof(*providers.ps));

	providers.ps[providers.len - 1] = p;
}

struct pass {
	int (*run)(struct pass *, struct ctx *);
	nwalk_fn pre;
	nwalk_fn post;
};


struct symtab syms = { .syms = NULL, .len = 0 };
/* symtab_t locals = { .sym = NULL, .len = 0 }; */

struct ctx *ctx_get(void)
{
	struct ctx *ctx;
	struct prog *prog;

	ctx = calloc(1, sizeof(*ctx));
	ctx->globals = calloc(1, sizeof(*ctx->globals));

	ctx->progs = calloc(3, sizeof(*ctx->progs));

	/* PROBE0 */
	prog = calloc(1, sizeof(*prog));
	prog->locals = calloc(1, sizeof(*prog->locals));
	prog->globals = ctx->globals;

	prog->probe = "k:SyS_read";

	/* { 
	 * 	# us = pid();
	 * 	t[0, pid()] = time();
	 * 	reads[pid()] = quantize(arg2);
	 * }
	 */
	prog->ast =
		node_expr(":block",
			  /* node_expr("=", */
			  /* 	    node_ident("us"), */
			  /* 	    node_expr("pid", NULL), */
			  /* 	    NULL), */
			  node_expr("=",
				    node_expr("{}",
					      node_ident("t"),
					      node_expr("pid", NULL),
					      node_num("0x10000000"),
					      NULL),
				    node_expr("time", NULL),
				    NULL),
			  /* node_expr("=", */
			  /* 	    node_expr("{}", */
			  /* 		      node_ident("reads"), */
			  /* 		      node_expr("pid", NULL), */
			  /* 		      NULL), */
			  /* 	    node_expr("quantize", node_ident("arg2"), NULL), */
			  /* 	    NULL), */
			  NULL);

	prog->provider = provider_get("k");
	prog->provider->probe(prog);
	prog->ir = ir_new();
	ctx->progs[0] = prog;

	/* PROBE1 */
	/* prog = calloc(1, sizeof(*prog)); */
	/* prog->locals = calloc(1, sizeof(*prog->locals)); */
	/* prog->globals = ctx->globals; */

	/* /\* TODO: k -> kret *\/ */
	/* prog->probe = "k:SyS_read2";  */
	/* /\* { times[pid()] = quantize(time() - t[0, pid()]) } *\/ */
	/* prog->ast = */
	/* 	node_expr("=", */
	/* 		  node_expr("{}", */
	/* 			    node_ident("times"), */
	/* 			    node_expr("pid", NULL), */
	/* 			    NULL), */
	/* 		  node_expr("quantize", */
	/* 			    node_expr("-", */
	/* 				      node_expr("time", NULL), */
	/* 				      node_expr("{}", */
	/* 						node_ident("t"), */
	/* 						node_num("0"), */
	/* 						node_expr("time", NULL), */
	/* 						node_expr("pid", NULL), */
	/* 						NULL), */
	/* 				      NULL), */
	/* 			    NULL), */
	/* 		  NULL); */

	/* prog->provider = provider_get("k"); */
	/* prog->provider->probe(prog); */
	/* prog->ir = ir_new(); */
	/* ctx->progs[1] = prog; */

	return ctx;
}


int pass_sym_alloc(struct node *n, void *_prog)
{
	struct prog *prog = _prog;
	struct provider *global = provider_get(":");
	int err = 0;

	if (n->sym)
		return 0;

	switch (n->ntype) {
	case N_EXPR:
	case N_IDENT:
		err = prog->provider->sym_alloc(prog, n);
		if (!err || (err != -ENOENT))
			break;

		err = global->sym_alloc(prog, n);
		break;
	case N_NUM:
	case N_STRING:
		err = global->sym_alloc(prog, n);
	}

	if (err) {
		if ((err == -ENOENT))
			_e("%#N: unknown symbol %N.\n", n, n);
	}

	return err;
}


int pass_type_infer(struct node *n, void *_prog)
{
	struct prog *prog = _prog;

	if (n->sym->func->type_infer)
		return n->sym->func->type_infer(n->sym->func, n);

	/* TODO recurse as long as we're infering new types */
	return 0;
}

int pass_rewrite(struct node *n, void *_prog)
{
	struct prog *prog = _prog;

	if (n->sym->func->rewrite)
		return n->sym->func->rewrite(n->sym->func, n, prog);

	return 0;
}

int pass_ir_pre(struct node *n, void *_prog)
{
	struct prog *prog = _prog;

	if (n->sym->func->ir_pre)
		return n->sym->func->ir_pre(n->sym->func, n, prog);

	return 0;
}

int pass_ir_post(struct node *n, void *_prog)
{
	struct prog *prog = _prog;

	if (n->sym->func->ir_post)
		return n->sym->func->ir_post(n->sym->func, n, prog);

	return 0;
}

int run_ir(struct pass *pass, struct ctx *ctx)
{
	struct prog **progp;
	int err;

	for (progp = ctx->progs; *progp; progp++) {
		struct prog *prog = *progp;

		err = prog->provider->ir_pre ?
			prog->provider->ir_pre(prog) : 0;
		if (err)
			return err;

		err = node_walk(prog->ast, pass_ir_pre, pass_ir_post, prog);
		if (err)
			return err;

		err = prog->provider->ir_post ?
			prog->provider->ir_post(prog) : 0;
		if (err)
			return err;

		ir_emit_insn(prog->ir, EXIT, 0, 0);
	}

	return 0;
}

int run_walk(struct pass *pass, struct ctx *ctx)
{
	struct prog **prog;
	int err;

	for (prog = ctx->progs; *prog; prog++) {
		err = node_walk((*prog)->ast, pass->pre, pass->post, *prog);
		if (err)
			return err;
	}

	return 0;
}

struct pass passes[] = {
	{ .run = run_walk, .post = pass_sym_alloc },
	{ .run = run_walk, .post = pass_type_infer },

	{ .run = run_walk, .post = pass_rewrite },

	{ .run = run_walk, .post = pass_sym_alloc },
	{ .run = run_walk, .post = pass_type_infer },

	{ .run = run_ir },
	/* program flattened to vBPF instructions, now rewrite it to
	 * fit into the actual hw/vm. */

	/* BPF program ready */
	{ NULL }
};

int main(void)
{
	struct ctx *ctx = ctx_get();
	struct prog **prog;
	struct pass *pass;
	int err = 0;

	for (pass = passes; pass->run; pass++) {
		err = pass->run(pass, ctx);
		if (err)
			break;
	}

	for (prog = ctx->progs; *prog; prog++) {
		printf("\n\e[34m%s\e[0m\n", (*prog)->probe);
		ast_fprint(stdout, (*prog)->ast);
		printf("\n-- locals\n");
		symtab_dump((*prog)->locals, stdout);
		printf("-- ir\n");
		ir_dump((*prog)->ir, stdout);
	}

	printf("\n\n-- globals\n");
	symtab_dump(ctx->globals, stdout);

	/* printf("\n\n-- decls\n"); */
	/* type_dump_decls(stdout); */

	if (err)
		printf("ERR: %d\n", err);

	return err;
}