/* $Id$ */
/*
   Copyright (C) 2004 - 2009 by Philippe Plantier <ayin@anathas.org>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License version 2
   or at your option any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

/**
 * @file builder.hpp
 * Definitions for the terrain builder.
 */

#ifndef BUILDER_H_INCLUDED
#define BUILDER_H_INCLUDED

#include "animated.hpp"
#include "image.hpp"
#include "map_location.hpp"

#include <map>
#include <set>

class config;

/**
 * The class terrain_builder is constructed from a config object, and a
 * gamemap object. On construction, it parses the configuration and extracts
 * the list of [terrain_graphics] rules. Each terrain_graphics rule attaches
 * one or more images to a specific terrain pattern.
 * It then applies the rules loaded from the configuration to the current map,
 * and calculates the list of images that must be associated to each hex of
 * the map.
 *
 * The get_terrain_at method can then be used to obtain the list of images
 * necessary to draw the terrain on a given tile.
 */
class terrain_builder
{
public:
	/** Used as a parameter for the get_terrain_at function. */
	enum ADJACENT_TERRAIN_TYPE {
			ADJACENT_BACKGROUND,	/**<
									 * Represents terrains which are to be
									 * drawn behind unit sprites
									 */
			ADJACENT_FOREGROUND	    /**<
									 * Represents terrains which are to be
									 * drawn in front of them.
									 */
	};

	/** A shorthand typedef for a list of animated image locators,
	 * the base data type returned by the get_terrain_at method.
	 */
	typedef std::vector<animated<image::locator> > imagelist;

	/** Constructor for the terrain_builder class.
	 *
	 * @param cfg			The main grame configuration object, where the
	 *						[terrain_graphics] rule reside.
	 * @param level		A level (scenario)-specific configuration file,
	 *		    containing scenario-specific [terrain_graphics] rules.
	 * @param map			A properly-initialized gamemap object representing
	 *						the current terrain map.
	 * @param offmap_image	The filename of the image which will be used as
	 *						off map image (see add_off_map_rule()).
	 *						This image automatically gets the 'terrain/' prefix
	 *						and '.png' suffix
	 */
	terrain_builder(const config& cfg, const config &level,
		const gamemap* map, const std::string& offmap_image);

	const gamemap& map() const { return *map_; }

	/**
	 * Updates internals that cache map size. This should be called when the map
	 * size has changed.
	 */
	void reload_map();

	void change_map(const gamemap* m);

	/** Returns a vector of strings representing the images to load & blit
	 * together to get the built content for this tile.
	 *
	 * @param loc   The location relative the the terrain map,
	 *				where we ask for the image list
	 * @param tod   The string representing the current time-of day.
	 *				Will be used if some images specify several
	 *				time-of-day- related variants.
	 * @param terrain_type ADJACENT_BACKGROUND or ADJACENT_FOREGROUND,
	 *              depending on wheter we ask for the terrain which is
	 *              before, or after the unit sprite.
	 *
	 * @return      Returns a pointer list of animated images corresponding
	 *              to the parameters, or NULL if there is none.
	 */
	const imagelist *get_terrain_at(const map_location &loc,
			const std::string &tod, ADJACENT_TERRAIN_TYPE const terrain_type);

	/** Updates the animation at a given tile.
	 * Returns true if something has changed, and must be redrawn.
	 *
	 * @param loc   the location to update
	 *
	 * @retval      true: this tile must be redrawn.
	 */
	bool update_animation(const map_location &loc);

	/** Performs a "quick-rebuild" of the terrain in a given location.
	 * The "quick-rebuild" is no proper rebuild: it only clears the
	 * terrain cache for a given location, and replaces it with a single,
	 * default image for this terrain.
	 *
	 * @param loc   the location where to rebuild terrains
	 */
	void rebuild_terrain(const map_location &loc);

	/** Performs a complete rebuild of the list of terrain graphics
	 * attached to a map.
	 * Should be called when a terrain is changed in the map.
	 */
	void rebuild_all();

	/**
	 * An image variant. The in-memory representation of the [variant]
	 * WML tag of the [image] WML tag. When an image only has one variant,
	 * the [variant] tag may be omitted.
	 */
	struct rule_image_variant {
		/** Shorthand constructor for this structure */
		rule_image_variant(const std::string &image_string, const std::string &tod) :
			image_string(image_string),
			image(),
			tod(tod)
			{};

		/** A string representing either the filename for an image, or
		 *  a list of images, with an optional timing for each image.
		 *  Corresponds to the "name" parameter of the [variant] (or of
		 *  the [image]) WML tag.
		 *
		 *  The timing string is in the following format (expressed in EBNF)
		 *
		 *@verbatim
		 *  <timing_string> ::= <timed_image> ( "," <timed_image> ) +
		 *
		 *  <timed_image> ::= <image_name> [ ":" <timing> ]
		 *
		 *  Where <image_name> represents the actual filename of an image,
		 *  and <timing> the number of milliseconds this image will last
		 *  in the animation.
		 *@endverbatim
		 */
		std::string image_string;

		/** An animated image locator built according to the image string.
		 * This will be the image locator which will actually
		 * be returned to the user.
		 */
		animated<image::locator> image;
		/**
		 * The time-of-day to which this variant applies.
		 * Set to the empty string, this variant applies to all TODs.
		 */
		std::string tod;
	};

	/**
	 * A map associating a rule_image_variant to a string representing
	 * the time of day.
	 */
	typedef std::map<std::string, rule_image_variant> rule_image_variantlist;

	/**
	 * Each terrain_graphics rule is associated a set of images, which are
	 * applied on the terrain if the rule matches. An image is more than
	 * graphics: it is graphics (with several possible tod-alternatives,)
	 * and a position for these graphics.
	 * The rule_image structure represents one such image.
	 */
	struct rule_image {
		rule_image(int layer, int x, int y, bool global_image=false, int center_x=-1, int center_y=-1);

		/** The layer of the image for horizontal layering */
		int layer;
		/** The position of the image base (that is, the point where
		 * the image reaches the floor) for vertical layering
		 */
		int basex, basey;

		/** A list of Time-Of-Day-related variants for this image
		 */
		rule_image_variantlist variants;

		/** Set to true if the image was defined as a child of the
		 * [terrain_graphics] tag, set to false if it was defined as a
		 * child of a [tile] tag */
		bool global_image;

		/** The position where the center of the image base should be
		 */
		int center_x, center_y;
	};

	/**
	 * A shorthand notation for a vector of rule_images
	 */
	typedef std::vector<rule_image> rule_imagelist;

	/**
	 * The in-memory representation of a [tile] WML rule
	 * inside of a [terrain_graphics] WML rule.
	 */
	struct terrain_constraint
	{
		terrain_constraint() :
			loc(),
			terrain_types_match(),
			set_flag(),
			no_flag(),
			has_flag(),
			images()
			{};

		terrain_constraint(map_location loc) :
			loc(loc),
			terrain_types_match(),
			set_flag(),
			no_flag(),
			has_flag(),
			images()
			{};

		map_location loc;
		t_translation::t_match terrain_types_match;
		std::vector<std::string> set_flag;
		std::vector<std::string> no_flag;
		std::vector<std::string> has_flag;
		rule_imagelist images;
	};

	/**
	 * Represents a tile of the game map, with all associated
	 * builder-specific parameters: flags, images attached to this tile,
	 * etc. An array of those tiles is built when terrains are built either
	 * during construction, or upon calling the rebuild_all() method.
	 */
	struct tile
	{
		/** An ordered rule_image list */
		typedef std::multimap<int, const rule_image*> ordered_ri_list;

		/** Contructor for the tile() structure */
		tile();

		/** Adds an image, extracted from an ordered rule_image list,
		 * to the background or foreground image cache.
		 *
		 * @param tod    The current time-of-day, to select between
		 *               images presenting several variants.
		 * @param itor   An iterator pointing to the rule_image where
		 *               to extract the image we wish to add to the
		 *               cache.
		 */
		void add_image_to_cache(const std::string &tod, ordered_ri_list::const_iterator itor);

		/** Rebuilds the whole image cache, for a given time-of-day.
		 * Must be called when the time-of-day has changed,
		 * to select the correct images.
		 *
		 * @param tod    The current time-of-day
		 */
		void rebuild_cache(const std::string &tod);

		/** Clears all data in this tile, and resets the cache */
		void clear();

		/** The list of flags present in this tile */
		std::set<std::string> flags;

		/** The list of images associated to this tile, ordered by
		 * their layer first and base-y position second.
		 */
		ordered_ri_list images;

		/** The list of images which are in front of the unit sprites,
		 * attached to this tile. This member is considered a cache:
		 * it is built once, and on-demand.
		 */
		imagelist images_foreground;
		/** The list of images which are behind the unit sprites,
		 * attached to this tile. This member is considered a cache:
		 * it is built once, and on-demand.
		 */
		imagelist images_background;
		/**
		 * The time-of-day to which the image caches correspond.
		 */
		std::string last_tod;

	};

private:
	/**
	 * The list of constraints attached to a terrain_graphics WML rule.
	 */
	typedef std::map<map_location, terrain_constraint> constraint_set;

	/**
	 * The in-memory representation of a [terrain_graphics] WML rule.
	 */
	struct building_rule
	{
		building_rule() :
			constraints(),
			location_constraints(),
			probability(0),
			precedence(0)
		{}

		/**
		 * The set of [tile] constraints of this rule.
		 */
		constraint_set constraints;

		/**
		 * The location on which this map may match.
		 * Set to a valid map_location if the "x" and "y" parameters
		 * of the [terrain_graphics] rule are set.
		 */
		map_location location_constraints;

		/**
		 * The probability of this rule to match, when all conditions
		 * are met. Defined if the "probability" parameter of the
		 * [terrain_graphics] element is set.
		 */
		int probability;

		/**
		 * The precedence of this rule. Used to order rules differently
		 * that the order in which they appear.
		 * Defined if the "precedence" parameter of the
		 * [terrain_graphics] element is set.
		 */
		int precedence;
	};

	/**
	 * The map of "tile" structures corresponding to the level map.
	 */
	class tilemap
	{
	public:
		/**
		 * Constructs a tilemap of dimensions x * y
		 */
		tilemap(int x, int y) :
				tiles_((x + 4) * (y + 4)),
				x_(x),
				y_(y)
			{}

		/**
		 * Returns a reference to the tile which is at the position
		 * pointed by loc. The location MUST be on the map!
		 *
		 * @param loc    The location of the tile
		 *
		 * @return		A reference to the tile at this location.
		 *
		 */
		tile &operator[](const map_location &loc);
		/**
		 * a const variant of operator[]
		 */
		const tile &operator[] (const map_location &loc) const;

		/**
		 * Tests if a location is on the map.
		 *
		 * @param loc   The location to test
		 *
		 * @return		true if loc is on the map, false otherwise.
		 */
		bool on_map(const map_location &loc) const;

		/**
		 * Resets the whole tile map
		 */
		void reset();

		/**
		 * Rebuilds the map to a new set of dimensions
		 */
		void reload(int x, int y);
	private:
		/** The map */
		std::vector<tile> tiles_;
		/** The x dimension of the map */
		int x_;
		/** The y dimension of the map */
		int y_;
	};

	/**
	 * A set of building rules. In-memory representation
	 * of the whole set of [terrain_graphics] rules.
	 */
	typedef std::multimap<int, building_rule> building_ruleset;

	/**
	 * Tests for validity of a rule. A rule is considered valid if all its
	 * images are present. This method is used, when building the ruleset,
	 * to only add rules which are valid to the ruleset.
	 *
	 * @param rule  The rule to test for validity
	 *
	 * @return		true if the rule is valid, false if it is not.
	 */
	bool rule_valid(const building_rule &rule) const;

	/**
	 * Starts the animation on a rule.
	 *
	 * @param rule  The rule on which ot start animations
	 *
	 * @return		true
	 */
	bool start_animation(building_rule &rule);

	/**
	 *  "Rotates" a constraint from a rule.
	 *  Takes a template constraint from a template rule, and creates
	 *  a constraint from this template, rotated to the given angle.
	 *
	 *  On a constraint, the relative position of each rule, and the "base"
	 *  of each vertical images, are rotated according to the given angle.
	 *
	 *  Template terrain constraints are defined like normal terrain
	 *  constraints, except that, flags, and image filenames,
	 *  may contain template strings of the form
	 *@verbatim
	 *  <code>@Rn</code>,
	 *@endverbatim
	 *  n being a number from 0 to 5.
	 *  See the rotate_rule method for more info.
	 *
	 *  @param constraint  A template constraint to rotate
	 *  @param angle       An int, from 0 to 5, representing the rotation angle.
	 */
	terrain_constraint rotate(const terrain_constraint &constraint, int angle);

	/**
	 * Replaces, in a given string, a token with its value.
	 *
	 * @param s            The string in which to do the replacement
	 * @param token        The token to substitute
	 * @param replacement  The replacement string
	 */
	void replace_token(std::string &s, const std::string &token,
			const std::string& replacement);

	/**
	 * Replaces, in a given rule_image, a token with its value.
	 * The actual substitution is done in all variants of the given image.
	 *
	 * @param image        The rule_image in which to do the replacement
	 * @param token        The token to substitute
	 * @param replacement  The replacement string
	 */
	void replace_token(rule_image &image, const std::string &token,
			const std::string& replacement);

	/**
	 * Replaces, in a given rule_variant_image, a token with its value.
	 * The actual substitution is done in the "image_string" parameter
	 * of this rule_variant_image.
	 *
	 * @param variant      The rule_variant_image in which to do the replacement
	 * @param token        The token to substitute
	 * @param replacement  The replacement string
	 */
	void replace_token(rule_image_variant &variant, const std::string &token,
			const std::string& replacement)
		{ replace_token(variant.image_string, token, replacement); }

	/**
	 * Replaces, in a given rule_imagelist, a token with its value.
	 * The actual substitution is done in all rule_images contained
	 * in the rule_imagelist.
	 *
	 * @param &					The rule_imagelist in which to do the replacement
	 * @param token		The token to substitute
	 * @param replacement		The replacement string
	 */
	void replace_token(rule_imagelist &, const std::string &token,
			const std::string& replacement);

	/**
	 * Replaces, in a given building_rule, a token with its value.
	 * The actual substitution is done in the rule_imagelists contained
	 * in all constraints of the building_rule, and in the flags
	 * (has_flag, set_flag and no_flag) contained in all constraints
	 * of the building_rule.
	 *
	 * @param rule         The building_rule in which to do the replacement
	 * @param token        The token to substitute
	 * @param replacement  The replacement string
	 */
	void replace_token(building_rule &rule, const std::string &token,
			const std::string& replacement);

	/**
	 *  Rotates a template rule to a given angle, and returns the rotated rule.
	 *
	 *  Template rules are defined like normal rules, except that:
	 *  * Flags and image filenames may contain template strings of the form
	 *@verbatim
	 *  <code>@Rn</code>, n being a number from 0 to 5.
	 *@endverbatim
	 *  * The rule contains the rotations=r0,r1,r2,r3,r4,r5, with r0 to r5
	 *    being strings describing the 6 different positions, typically,
	 *    n, ne, se, s, sw, and nw (but maybe anything else.)
	 *
	 *  A template rule will generate 6 rules, which are similar
	 *  to the template, except that:
	 *
	 *  * The map of constraints ( [tile]s ) of this rule will be
	 *    rotated by an angle, of 0 to 5 pi / 6
	 *
	 *  * On the rule which is rotated to 0rad, the template strings
	 *@verbatim
	 *    @R0, @R1, @R2, @R3, @R4, @R5,
	 *@endverbatim
	 *    will be replaced by the corresponding r0, r1, r2, r3, r4, r5
	 *    variables given in the rotations= element.
	 *
	 *  * On the rule which is rotated to pi/3 rad, the template strings
	 *@verbatim
	 *    @R0, @R1, @R2 etc.
	 *@endverbatim
	 *    will be replaced by the corresponding
	 *    <strong>r1, r2, r3, r4, r5, r0</strong> (note the shift in indices).
	 *
	 *  * On the rule rotated 2pi/3, those will be replaced by
	 *    r2, r3, r4, r5, r0, r1 and so on.
	 *
	 */
	building_rule rotate_rule(const building_rule &rule, int angle,
							  const std::vector<std::string>& angle_name);

	/**
	 * Parses a "config" object, which should contains [image] children,
	 * and adds the corresponding parsed rule_images to a rule_imagelist.
	 *
	 * @param images   The rule_imagelist into which to add the parsed images.
	 * @param cfg      The WML configuration object to parse
	 * @param global   Whether those [image]s elements belong to a
	 *                 [terrain_graphics] element, or to a [tile] child.
	 *                 Set to true if those belong to a [terrain_graphics]
	 *                 element.
	 * @param dx       The X coordinate of the constraint those images
	 *                 apply to, relative to the start of the rule. Only
	 *                 meaningful if global is set to false.
	 * @param dy       The Y coordinate of the constraint those images
	 *                 apply to.
	 */
	void add_images_from_config(rule_imagelist &images, const config &cfg, bool global,
			int dx=0, int dy=0);


	/**
	 * Creates a rule constraint object which matches a given list of
	 * terrains, and adds it to the list of constraints of a rule.
	 *
	 * @param constraints  The constraint set to which to add the constraint.
	 * @param loc           The location of the constraint
	 * @param type          The list of terrains this constraint will match
	 * @param global_images A configuration object containing [image] tags
	 *                      describing rule-global images.
	 */
	void add_constraints(constraint_set& constraints,
			const map_location &loc, const t_translation::t_match& type,
			const config& global_images);

	/**
	 * Creates a rule constraint object from a config object and
	 * adds it to the list of constraints of a rule.
	 *
	 * @param constraints   The constraint set to which to add the constraint.
	 * @param loc           The location of the constraint
	 * @param cfg           The config object describing this constraint.
	 *                      Usually, a [tile] child of a [terrain_graphics] rule.
	 * @param global_images A configuration object containing [image] tags
	 *                      describing rule-global images.
	 */
	void add_constraints(constraint_set& constraints,
			const map_location &loc, const config &cfg,
			const config& global_images);

	typedef std::multimap<int, map_location> anchormap;

	/**
	 * Parses a map string (the map= element of a [terrain_graphics] rule,
	 * and adds constraints from this map to a building_rule.
	 *
	 * @param mapstring     The map vector to parse
	 * @param br            The building rule into which to add the extracted
	 *                      constraints
	 * @param anchors       A map where to put "anchors" extracted from the map.
	 * @param global_images A config object representing the images defined
	 *                      as direct children of the [terrain_graphics] rule.
	 */
	void parse_mapstring(const std::string &mapstring, struct building_rule &br,
			     anchormap& anchors, const config& global_images);

	/**
	 * Adds a rule to a ruleset. Checks for validity before adding the rule.
	 *
	 * @param rules   The ruleset into which to add the rules.
	 * @param rule    The rule to add.
	 */
	void add_rule(building_ruleset& rules, building_rule &rule);

	/**
	 * Adds a set of rules to a ruleset, from a template rule which spans
	 * 6 rotations (or less if some of the rotated rules are invalid).
	 *
	 * @param rules      The ruleset into which to add the rules.
	 * @param tpl        The template rule
	 * @param rotations  A comma-separated string containing the
	 *					 6 values for replacing rotation
	 *					 template strings @verbatim (@Rn) @endverbatim
	 */
	void add_rotated_rules(building_ruleset& rules, building_rule& tpl, const std::string &rotations);

	/**
	 * Parses a configuration object containing [terrain_graphics] rules,
	 * and fills the building_rules_ member of the current class according
	 * to those.
	 *
	 * @param cfg		The configuration object to parse.
	 */
	void parse_config(const config &cfg);

	/**
	 * Adds a builder rule for the _off^_usr tile, this tile only has 1 image.
	 *
	 * @param image		The filename of the image
	 */
	void add_off_map_rule(const std::string& image);

	/**
	 * Checks whether a terrain code matches a given list of terrain codes.
	 *
	 * @param tcode 	The terrain to check
	 * @param terrains	The terrain list agains which to check the terrain.
	 *	May contain the metacharacters
	 *	- '*' STAR, meaning "all terrains"
	 *	- '!' NOT,  meaning "all terrains except those present in the list."
	 *
	 * @return			returns true if "tcode" matches the list or the list is empty,
	 *					else false.
	 */
	bool terrain_matches(t_translation::t_terrain tcode, const t_translation::t_list& terrains) const
		{ return terrains.empty()? true : t_translation::terrain_matches(tcode, terrains); }

	/**
	 * Checks whether a terrain code matches a given list of terrain tcodes.
	 *
	 * @param tcode 	The terrain code to check
	 * @param terrain	The terrain match structure which to check the terrain.
	 *	See previous definition for more details.
	 *
	 * @return			returns true if "tcode" matches the list or the list is empty,
	 *					else false.
	 */
	bool terrain_matches(t_translation::t_terrain tcode, const t_translation::t_match &terrain) const
		{ return terrain.is_empty ? true : t_translation::terrain_matches(tcode, terrain); }

	/**
	 * Checks whether a rule matches a given location in the map.
	 *
	 * @param rule      The rule to check.
	 * @param loc       The location in the map where we want to check
	 *                  whether the rule matches.
	 * @param rule_index The index of the rule, relative to the start of
	 *                  the rule list. Rule indices are used for seeding
	 *                  the pseudo-random-number generator used for
	 *                  probability calculations.
	 * @param type_checked The constraint which we already know that its
	 *                  terrain types matches.
	 */
	bool rule_matches(const building_rule &rule, const map_location &loc,
			const int rule_index, const constraint_set::const_iterator type_checked) const;

	/**
	 * Applies a rule at a given location: applies the result of a
	 * matching rule at a given location: attachs the images corresponding
	 * to the rule, and sets the flags corresponding to the rule.
	 *
	 * @param rule      The rule to apply
	 * @param loc       The location to which to apply the rule.
	 */
	void apply_rule(const building_rule &rule, const map_location &loc);

	/**
	 * Calculates the list of terrains, and fills the tile_map_ member,
	 * from the gamemap and the building_rules_.
	 */
	void build_terrains();

	/**
	 * A pointer to the gamemap class used in the current level.
	 */
	const gamemap* map_;

	/**
	 * The tile_map_ for the current level, which is filled by the
	 * build_terrains_ method to contain "tiles" representing images
	 * attached to each tile.
	 */
	tilemap tile_map_;

	/**
	 * Shorthand typedef for a map associating a list of locations to a terrain type.
	 */
	typedef std::map<t_translation::t_terrain, std::vector<map_location> > terrain_by_type_map;

	/**
	 * A map representing all locations whose terrain is of a given type.
	 */
	terrain_by_type_map terrain_by_type_;

	building_ruleset building_rules_;

};

#endif