/*
See vpr/SRC/route/build_switchblocks.c for a detailed description of how the new
switch block format works and what files are involved.

 
A large chunk of this file is dedicated to helping parse the initial switchblock
specificaiton in the XML arch file, providing error checking, etc.

Another large chunk of this file is dedicated to parsing the actual formulas 
specified by the switch block permutation functions into their numeric counterparts.
*/


#include <string.h>
#include <string>
#include <sstream>
#include <vector>
#include <stack>
#include <utility>
#include <algorithm>

#include "vtr_assert.h"
#include "vtr_util.h"

#include "pugixml.hpp"
#include "pugixml_util.hpp"

#include "arch_error.h"

#include "read_xml_util.h"
#include "arch_util.h"
#include "arch_types.h"
#include "physical_types.h"
#include "parse_switchblocks.h"


using namespace std;
using namespace pugiutil;


/**** Function Declarations ****/
/*---- Functions for Parsing Switchblocks from Architecture ----*/

//Load an XML wireconn specification into a t_wireconn_inf 
t_wireconn_inf parse_wireconn(pugi::xml_node node, const pugiutil::loc_data& loc_data);

//Process a wireconn defined in the inline style (using attributes)
void parse_wireconn_inline(pugi::xml_node node, const pugiutil::loc_data& loc_data, t_wireconn_inf& wc);

//Process a wireconn defined in the multinode style (more advanced specification)
void parse_wireconn_multinode(pugi::xml_node node, const pugiutil::loc_data& loc_data, t_wireconn_inf& wc);

//Process a <from> or <to> sub-node of a multinode wireconn
t_wire_switchpoints parse_wireconn_from_to_node(pugi::xml_node node, const pugiutil::loc_data& loc_data);

/* parses the wire types specified in the comma-separated 'ch' char array into the vector wire_points_vec. 
   Spaces are trimmed off */
static void parse_comma_separated_wire_types(const char *ch, std::vector<t_wire_switchpoints>& wire_switchpoints);

/* parses the wirepoints specified in ch into the vector wire_points_vec */
static void parse_comma_separated_wire_points(const char *ch, std::vector<t_wire_switchpoints>& wire_switchpoints);

/* Parses the number of connections type */
static void parse_num_conns(std::string num_conns, t_wireconn_inf& wireconn);

/* checks for correctness of a unidir switchblock. */
static void check_unidir_switchblock(const t_switchblock_inf *sb );

/* checks for correctness of a bidir switchblock. */
static void check_bidir_switchblock(const t_permutation_map *permutation_map );

/* checks for correctness of a wireconn segment specification. */
static void check_wireconn(const t_arch* arch, const t_wireconn_inf& wireconn);


/**** Function Definitions ****/

/*---- Functions for Parsing Switchblocks from Architecture ----*/

/* Reads-in the wire connections specified for the switchblock in the xml arch file */
void read_sb_wireconns(const t_arch_switch_inf * /*switches*/, int /*num_switches*/, pugi::xml_node Node, t_switchblock_inf *sb, const pugiutil::loc_data& loc_data ){
	
	/* Make sure that Node is a switchblock */
	check_node(Node, "switchblock", loc_data);
	
	int num_wireconns;
	pugi::xml_node SubElem;

	/* count the number of specified wire connections for this SB */
	num_wireconns = count_children(Node, "wireconn", loc_data, OPTIONAL);
	sb->wireconns.reserve(num_wireconns);

	if (num_wireconns > 0) {
		SubElem = get_first_child(Node, "wireconn", loc_data);	
	}
	for (int i = 0; i < num_wireconns; i++){
        t_wireconn_inf wc = parse_wireconn(SubElem, loc_data);
		sb->wireconns.push_back(wc);
		SubElem = SubElem.next_sibling(SubElem.name());
	}

	return;
}

t_wireconn_inf parse_wireconn(pugi::xml_node node, const pugiutil::loc_data& loc_data) {
    t_wireconn_inf wc;

    size_t num_attributes = count_attributes(node, loc_data);

    if (num_attributes == 1) {
        parse_wireconn_multinode(node, loc_data, wc);
    } else {
        VTR_ASSERT(num_attributes > 0);
        parse_wireconn_inline(node, loc_data, wc);
    }


    return wc;
}

void parse_wireconn_inline(pugi::xml_node node, const pugiutil::loc_data& loc_data, t_wireconn_inf& wc) {
    //Parse an inline wireconn definition, using attributes

    /* get the connection style */
    const char* char_prop = get_attribute(node, "num_conns_type", loc_data).value();
    parse_num_conns(char_prop, wc);

    /* get from type */
    char_prop = get_attribute(node, "from_type", loc_data).value();
    parse_comma_separated_wire_types(char_prop, wc.from_switchpoint_set);

    /* get to type */
    char_prop = get_attribute(node, "to_type", loc_data).value();
    parse_comma_separated_wire_types(char_prop, wc.to_switchpoint_set);

    /* get the source wire point */
    char_prop = get_attribute(node, "from_switchpoint", loc_data).value();
    parse_comma_separated_wire_points(char_prop, wc.from_switchpoint_set);

    /* get the destination wire point */
    char_prop = get_attribute(node, "to_switchpoint", loc_data).value();
    parse_comma_separated_wire_points(char_prop, wc.to_switchpoint_set);
}

void parse_wireconn_multinode(pugi::xml_node node, const pugiutil::loc_data& loc_data, t_wireconn_inf& wc) {
    /* get the connection style */
    const char* char_prop = get_attribute(node, "num_conns_type", loc_data).value();
    parse_num_conns(char_prop, wc);

    size_t num_from_children = count_children(node, "from", loc_data);
    size_t num_to_children = count_children(node, "to", loc_data);

    VTR_ASSERT(num_from_children > 0);
    VTR_ASSERT(num_to_children > 0);

    for (pugi::xml_node child : node.children()) {
        if (child.name() == std::string("from")) {
            t_wire_switchpoints from_switchpoints = parse_wireconn_from_to_node(child, loc_data);
            wc.from_switchpoint_set.push_back(from_switchpoints);
        } else if (child.name() == std::string("to")) {
            t_wire_switchpoints to_switchpoints = parse_wireconn_from_to_node(child, loc_data);
            wc.to_switchpoint_set.push_back(to_switchpoints);
        } else {
            archfpga_throw(loc_data.filename_c_str(), loc_data.line(node), "Unrecognized child node '%s' of parent node '%s'",
                            node.name(), child.name());
        }
    }
}

t_wire_switchpoints parse_wireconn_from_to_node(pugi::xml_node node, const pugiutil::loc_data& loc_data) {
    size_t attribute_count = count_attributes(node, loc_data);

    if (attribute_count != 2) {
        archfpga_throw(loc_data.filename_c_str(), loc_data.line(node), "Expected only 2 attributes on node '%s'",
                        node.name());
    }

    t_wire_switchpoints wire_switchpoints;
    wire_switchpoints.segment_name = get_attribute(node, "type", loc_data).value();

    auto points_str = get_attribute(node, "switchpoint", loc_data).value();
    for (const auto& point_str : vtr::split(points_str, ",")) {
        int switchpoint = vtr::atoi(point_str);
        wire_switchpoints.switchpoints.push_back(switchpoint);
    }

    if (wire_switchpoints.switchpoints.empty()) {
        archfpga_throw(loc_data.filename_c_str(), loc_data.line(node), "Empty switchpoint specification",
                        node.name());
    }

    return wire_switchpoints;
}

/* parses the wire types specified in the comma-separated 'ch' char array into the vector wire_points_vec. 
   Spaces are trimmed off */
static void parse_comma_separated_wire_types(const char *ch, std::vector<t_wire_switchpoints>& wire_switchpoints) {
    auto types = vtr::split(ch, ",");

    if (types.empty()){
        archfpga_throw( __FILE__, __LINE__, "parse_comma_separated_wire_types: found empty wireconn wire type entry\n");
    }

    for (const auto& type : types) {
        t_wire_switchpoints wsp;
        wsp.segment_name = type;

        wire_switchpoints.push_back(wsp);
    }
}


/* parses the wirepoints specified in the comma-separated 'ch' char array into the vector wire_points_vec */
static void parse_comma_separated_wire_points(const char *ch, std::vector<t_wire_switchpoints>& wire_switchpoints){
    auto points = vtr::split(ch, ",");
    if (points.empty()){
        archfpga_throw( __FILE__, __LINE__, "parse_comma_separated_wire_points: found empty wireconn wire point entry\n");
    }

    for(const auto& point_str : points) {
        int point = vtr::atoi(point_str);

        for(auto& wire_switchpoint : wire_switchpoints) {
            wire_switchpoint.switchpoints.push_back(point);
        }
    }
}

static void parse_num_conns(std::string num_conns, t_wireconn_inf& wireconn) {

    if (num_conns == "from") {
        wireconn.num_conns_type = WireConnType::FROM;
    } else if (num_conns == "to") {
        wireconn.num_conns_type = WireConnType::TO;
    } else if (num_conns == "min") {
        wireconn.num_conns_type = WireConnType::MIN;
    } else if (num_conns == "max") {
        wireconn.num_conns_type = WireConnType::MAX;
    } else {
		archfpga_throw( __FILE__, __LINE__, "Invalid num_conns specification '%s'", num_conns.c_str());
    }
}

/* Loads permutation funcs specified under Node into t_switchblock_inf. Node should be 
   <switchfuncs> */
void read_sb_switchfuncs( pugi::xml_node Node, t_switchblock_inf *sb, const pugiutil::loc_data& loc_data ){
	
	/* Make sure the passed-in is correct */
	check_node(Node, "switchfuncs", loc_data);
	
	pugi::xml_node SubElem;

	/* get the number of specified permutation functions */
	int num_funcs = count_children(Node, "func", loc_data, OPTIONAL);

	const char * func_type;
	const char * func_formula;
	vector<string> * func_ptr;

	/* used to index into permutation map of switchblock */
	SB_Side_Connection conn;

	/* now we iterate through all the specified permutation functions, and 
	   load them into the switchblock structure as appropriate */
	if (num_funcs > 0) {
		SubElem = get_first_child(Node, "func", loc_data);	
	}
	for (int ifunc = 0; ifunc < num_funcs; ifunc++){

		/* get function type */
		func_type = get_attribute(SubElem, "type", loc_data).as_string(nullptr);

		/* get function formula */
		func_formula = get_attribute(SubElem, "formula", loc_data).as_string(nullptr);

		/* go through all the possible cases of func_type */
		if (0 == strcmp(func_type, "lt")){
			conn.set_sides(LEFT, TOP);
		} else if (0 == strcmp(func_type, "lr")) {
			conn.set_sides(LEFT, RIGHT);
		} else if (0 == strcmp(func_type, "lb")) {
			conn.set_sides(LEFT, BOTTOM);
		} else if (0 == strcmp(func_type, "tl")) {
			conn.set_sides(TOP, LEFT);
		} else if (0 == strcmp(func_type, "tb")) {
			conn.set_sides(TOP, BOTTOM);
		} else if (0 == strcmp(func_type, "tr")) {
			conn.set_sides(TOP, RIGHT);
		} else if (0 == strcmp(func_type, "rt")) {
			conn.set_sides(RIGHT, TOP);
		} else if (0 == strcmp(func_type, "rl")) {
			conn.set_sides(RIGHT, LEFT);
		} else if (0 == strcmp(func_type, "rb")) {
			conn.set_sides(RIGHT, BOTTOM);
		} else if (0 == strcmp(func_type, "bl")) {
			conn.set_sides(BOTTOM, LEFT);
		} else if (0 == strcmp(func_type, "bt")) {
			conn.set_sides(BOTTOM, TOP);
		} else if (0 == strcmp(func_type, "br")) {
			conn.set_sides(BOTTOM, RIGHT);
		} else {
			/* unknown permutation function */
			archfpga_throw( __FILE__, __LINE__, "Unknown permutation function specified: %s\n", func_type);
		}
		func_ptr = &(sb->permutation_map[conn]);

		/* Here we load the specified switch function(s) */
		func_ptr->push_back( string(func_formula) );
 
		func_ptr = nullptr;
		/* get the next switchblock function */
		SubElem = SubElem.next_sibling(SubElem.name());
	}

	return;
}


/* checks for correctness of switch block read-in from the XML architecture file */
void check_switchblock(const t_switchblock_inf* sb, const t_arch* arch){

	/* get directionality */
	enum e_directionality directionality = sb->directionality;

	/* Check for errors in the switchblock descriptions */
	if (UNI_DIRECTIONAL == directionality){
		check_unidir_switchblock( sb );
	} else {
		VTR_ASSERT(BI_DIRECTIONAL == directionality);
		check_bidir_switchblock( &(sb->permutation_map) );
	}


	/* check that specified wires exist */
    for (const auto& wireconn : sb->wireconns) {

        check_wireconn(arch, wireconn);
    }

	//TODO:
	/* check that the wire segment directionality matches the specified switch block directionality */
	/* check for duplicate names */
	/* check that specified switches exist */
	/* check that type of switchblock matches type of switch specified */
}


/* checks for correctness of a unidirectional switchblock. hard exit if error found (to be changed to throw later) */
static void check_unidir_switchblock(const t_switchblock_inf *sb ){

	/* Check that the destination wire points are always the starting points (i.e. of wire point 0) */
	for (const t_wireconn_inf& wireconn : sb->wireconns){
        for (const t_wire_switchpoints& wire_to_points : wireconn.to_switchpoint_set) {
            if (wire_to_points.switchpoints.size() > 1 || wire_to_points.switchpoints[0] != 0){
                archfpga_throw( __FILE__, __LINE__, "Unidirectional switch blocks are currently only allowed to drive the start points of wire segments\n");
            }
        }
	}
}


/* checks for correctness of a bidirectional switchblock */
static void check_bidir_switchblock(const t_permutation_map *permutation_map ){
	/**** check that if side1->side2 is specified, then side2->side1 is not, as it is implicit ****/

	/* variable used to index into the permutation map */
	SB_Side_Connection conn;

	/* iterate over all combinations of from_side -> to side */
	for (e_side from_side : {TOP, RIGHT, BOTTOM, LEFT}) {
		for (e_side to_side : {TOP, RIGHT, BOTTOM, LEFT}) {
			/* can't connect a switchblock side to itself */
			if (from_side == to_side){
				continue;
			}

			/* index into permutation map with this variable */			
			conn.set_sides(from_side, to_side);

			/* check if a connection between these sides exists */
			t_permutation_map::const_iterator it = (*permutation_map).find(conn);
			if (it != (*permutation_map).end()){
				/* the two sides are connected */
				/* check if the opposite connection has been specified */
				conn.set_sides(to_side, from_side);
				it = (*permutation_map).find(conn);
				if (it != (*permutation_map).end()){
					archfpga_throw( __FILE__, __LINE__, "If a bidirectional switch block specifies a connection from side1->side2, no connection should be specified from side2->side1 as it is implicit.\n");
				}
			}
		}
	}

	return;
}

static void check_wireconn(const t_arch* arch, const t_wireconn_inf& wireconn) {
    for (const t_wire_switchpoints& wire_switchpoints : wireconn.from_switchpoint_set) {
        auto seg_name = wire_switchpoints.segment_name;

        //Make sure the segment exists
        const t_segment_inf* seg_info = find_segment(arch, seg_name);
        if (!seg_info) {
            archfpga_throw( __FILE__, __LINE__, "Failed to find segment '%s' for <wireconn> from type specification\n", seg_name.c_str());
        }

        //Check that the specified switch points are valid
        for(int switchpoint : wire_switchpoints.switchpoints) {
            if (switchpoint < 0) {
                archfpga_throw( __FILE__, __LINE__, "Invalid <wireconn> from_switchpoint '%d' (must be >= 0)\n", switchpoint, seg_name.c_str());
            }
            if (switchpoint >= seg_info->length) {
                archfpga_throw( __FILE__, __LINE__, "Invalid <wireconn> from_switchpoints '%d' (must be < %d)\n", switchpoint, seg_info->length);
            }
            //TODO: check that points correspond to valid sb locations
        }
    }

    for (const t_wire_switchpoints& wire_switchpoints : wireconn.to_switchpoint_set) {
        auto seg_name = wire_switchpoints.segment_name;

        //Make sure the segment exists
        const t_segment_inf* seg_info = find_segment(arch, seg_name);
        if (!seg_info) {
            archfpga_throw( __FILE__, __LINE__, "Failed to find segment '%s' for <wireconn> to type specification\n", seg_name.c_str());
        }

        //Check that the specified switch points are valid
        for(int switchpoint : wire_switchpoints.switchpoints) {
            if (switchpoint < 0) {
                archfpga_throw( __FILE__, __LINE__, "Invalid <wireconn> to_switchpoint '%d' (must be >= 0)\n", switchpoint, seg_name.c_str());
            }
            if (switchpoint >= seg_info->length) {
                archfpga_throw( __FILE__, __LINE__, "Invalid <wireconn> to_switchpoints '%d' (must be < %d)\n", switchpoint, seg_info->length);
            }
            //TODO: check that points correspond to valid sb locations
        }
    }

}

/*---- Functions for Parsing the Symbolic Switchblock Formulas ----*/

/* returns integer result according to the specified switchblock formula and data. formula may be piece-wise */
int get_sb_formula_raw_result( const char* formula, const t_formula_data &mydata ){
	/* the result of the formula will be an integer */
	int result = -1;

	/* check formula */
	if (nullptr == formula){
		archfpga_throw( __FILE__, __LINE__, "in get_sb_formula_result: SB formula pointer NULL\n");
	} else if ('\0' == formula[0]){
		archfpga_throw( __FILE__, __LINE__, "in get_sb_formula_result: SB formula empty\n");
	}

	/* parse based on whether formula is piece-wise or not */
	if ( is_piecewise_formula(formula) ){
		//EXPERIMENTAL
		result = parse_piecewise_formula( formula, mydata );
	} else {
		result = parse_formula( formula, mydata );
	}
	
	return result;
}