/** \file history.h
  Prototypes for history functions, part of the user interface.
*/

#ifndef FISH_HISTORY_H
#define FISH_HISTORY_H

#include <wchar.h>
#include "common.h"
#include "pthread.h"
#include <vector>
#include <utility>
#include <list>
#include <tr1/memory>
#include <set>

typedef std::list<wcstring> path_list_t;

enum history_search_type_t {
    /** The history searches for strings containing the given string */
    HISTORY_SEARCH_TYPE_CONTAINS,
    
    /** The history searches for strings starting with the given string */
    HISTORY_SEARCH_TYPE_PREFIX
};

class history_item_t {
    friend class history_t;
    friend class history_lru_node_t;
    friend class history_tests_t;

    private:
    explicit history_item_t(const wcstring &);
    explicit history_item_t(const wcstring &, time_t, const path_list_t &paths = path_list_t());
    
    /** Attempts to merge two compatible history items together */
    bool merge(const history_item_t &item);

	/** The actual contents of the entry */
	wcstring contents;
    
	/** Original creation time for the entry */
	time_t creation_timestamp;
    
    /** Paths that we require to be valid for this item to be autosuggested */
    path_list_t required_paths;
    
    public:
    const wcstring &str() const { return contents; }
    bool empty() const { return contents.empty(); }
    
    /* Whether our contents matches a search term. */
    bool matches_search(const wcstring &term, enum history_search_type_t type) const;
    
    time_t timestamp() const { return creation_timestamp; }
    
    const path_list_t &get_required_paths() const { return required_paths; }
    
    bool operator==(const history_item_t &other) const {
        return contents == other.contents &&
               creation_timestamp == other.creation_timestamp &&
               required_paths == other.required_paths;
    }
};

/* The type of file that we mmap'd */
enum history_file_type_t {
    history_type_unknown,
    history_type_fish_2_0,
    history_type_fish_1_x
};

class history_t {
    friend class history_tests_t;
private:
    /** No copying */
    history_t(const history_t&);
    history_t &operator=(const history_t&);

    /** Private creator */
    history_t(const wcstring &pname);
    
    /** Privately add an item */
    void add(const history_item_t &item);
    
    /** Destructor */
    ~history_t();

    /** Lock for thread safety */
    pthread_mutex_t lock;
    
    /** Internal function */
    void clear_file_state();

	/** The name of this list. Used for picking a suitable filename and for switching modes. */
	const wcstring name;
	
	/** New items. */
	std::vector<history_item_t> new_items;

  	/** Deleted item contents. */
	std::set<wcstring> deleted_items;

	/** How many items we've added without saving */
	size_t unsaved_item_count;
    
	/** The mmaped region for the history file */
	const char *mmap_start;

	/** The size of the mmap'd region */
	size_t mmap_length;

    /** The type of file we mmap'd */
    history_file_type_t mmap_type;

    /** Timestamp of when this history was created */
    const time_t birth_timestamp;

	/** Timestamp of last save */
	time_t save_timestamp;
    
    void populate_from_mmap(void);
    
    /** List of old items, as offsets into out mmap data */
    std::vector<size_t> old_item_offsets;
    
    /** Whether we've loaded old items */
    bool loaded_old;
    
    /** Loads old if necessary */
    bool load_old_if_needed(void);
    
    /** Deletes duplicates in new_items. */
    void compact_new_items();
    
    /** Saves history */
    void save_internal();

    /* Versioned decoding */
    static history_item_t decode_item_fish_2_0(const char *base, size_t len);
    static history_item_t decode_item_fish_1_x(const char *base, size_t len);
    static history_item_t decode_item(const char *base, size_t len, history_file_type_t type);
        
public:
    /** Returns history with the given name, creating it if necessary */
    static history_t & history_with_name(const wcstring &name);
    
    /** Determines whether the history is empty. Unfortunately this cannot be const, since it may require populating the history. */
    bool is_empty(void);
    
    /** Add a new history item to the end */
    void add(const wcstring &str, const path_list_t &valid_paths = path_list_t());

    /** Remove a history item */
    void remove(const wcstring &str);
    
    /** Add a new history item to the end */
    void add_with_file_detection(const wcstring &str);
    
    /** Saves history */
    void save();
    
    /** Irreversibly clears history */
    void clear();
    
    /** Populates from a bash history file */
    void populate_from_bash(FILE *f);
    
    /* Gets all the history into a string with ARRAY_SEP_STR. This is intended for the $history environment variable. This may be long! */
    void get_string_representation(wcstring &str, const wcstring &separator);
    
    /** Return the specified history at the specified index. 0 is the index of the current commandline. (So the most recent item is at index 1.) */
    history_item_t item_at_index(size_t idx);
    
    bool is_deleted(const history_item_t &item) const;
};

class history_search_t {

    /** The history in which we are searching */
    history_t * history;
    
    /** Our type */
    enum history_search_type_t search_type;
    
    /** Our list of previous matches as index, value. The end is the current match. */
    typedef std::pair<size_t, history_item_t> prev_match_t;
    std::vector<prev_match_t> prev_matches;

    /** Returns yes if a given term is in prev_matches. */
    bool match_already_made(const wcstring &match) const;

    /** The search term */
    wcstring term;
    
    /** Additional strings to skip (sorted) */
    wcstring_list_t external_skips;
    
    bool should_skip_match(const wcstring &str) const;
    
    public:
    
    /** Gets the search term */
    const wcstring &get_term() const { return term; }

    /** Sets additional string matches to skip */
    void skip_matches(const wcstring_list_t &skips);

    /** Finds the next search term (forwards in time). Returns true if one was found. */
    bool go_forwards(void);
    
    /** Finds the previous search result (backwards in time). Returns true if one was found. */
    bool go_backwards(void);
    
    /** Goes to the end (forwards) */
    void go_to_end(void);
    
    /** Returns if we are at the end. We start out at the end. */
    bool is_at_end(void) const;
    
    /** Goes to the beginning (backwards) */
    void go_to_beginning(void);
    
    /** Returns the current search result item. asserts if there is no current item. */
    history_item_t current_item(void) const;
    
    /** Returns the current search result item contents. asserts if there is no current item. */
    wcstring current_string(void) const;


    /** Constructor */
    history_search_t(history_t &hist, const wcstring &str, enum history_search_type_t type = HISTORY_SEARCH_TYPE_CONTAINS) :
        history(&hist),
        search_type(type),
        term(str)
    {}
    
    /* Default constructor */
    history_search_t() :
        history(),
        search_type(HISTORY_SEARCH_TYPE_CONTAINS),
        term()
    {}
    
};



/**
   Init history library. The history file won't actually be loaded
   until the first time a history search is performed.
*/
void history_init();

/**
   Saves the new history to disc.
*/
void history_destroy();

/**
   Perform sanity checks
*/
void history_sanity_check();

/* A helper class for threaded detection of paths */
struct file_detection_context_t {

    /* Constructor */
    file_detection_context_t(history_t *hist, const wcstring &cmd);
    
    /* Determine which of potential_paths are valid, and put them in valid_paths */
    int perform_file_detection();
    
    /* The history associated with this context */
    history_t *history;
    
    /* The command */
    wcstring command;
    
    /* When the command was issued */
    time_t when;
    
    /* The working directory at the time the command was issued */
    wcstring working_directory;
    
    /* Paths to test */
    path_list_t potential_paths;
    
    /* Paths that were found to be valid */
    path_list_t valid_paths;
    
    /* Performs file detection. Returns 1 if every path in potential_paths is valid, 0 otherwise. If test_all is true, tests every path; otherwise stops as soon as it reaches an invalid path. */
    int perform_file_detection(bool test_all);
    
    /* Determine whether the given paths are all valid */
    bool paths_are_valid(const path_list_t &paths);
};

#endif