/** Copyright 2011-2013 Thorsten Wißmann. All rights reserved.
 *
 * This software is licensed under the "Simplified BSD License".
 * See LICENSE for details */

#include "rules.h"
#include "globals.h"
#include "utils.h"
#include "ewmh.h"
#include "clientlist.h"
#include "ipc-protocol.h"
#include "hook.h"
#include "command.h"

#include "glib-backports.h"
#include "glib-backports.h"
#include <string.h>
#include <stdio.h>
#include <sys/types.h>

/// TYPES ///

typedef struct {
    const char*   name;
    bool    (*matches)(HSCondition* condition, HSClient* client);
} HSConditionType;

typedef struct {
    const char*   name;
    void    (*apply)(HSConsequence* consequence, HSClient* client,
                     HSClientChanges* changes);
} HSConsequenceType;

/// DECLARATIONS ///
static int find_condition_type(const char* name);
static int find_consequence_type(const char* name);
static bool condition_string(HSCondition* rule, const char* string);

/// CONDITIONS ///
#define DECLARE_CONDITION(NAME)                         \
    static bool NAME(HSCondition* rule, HSClient* client)

DECLARE_CONDITION(condition_class);
DECLARE_CONDITION(condition_instance);
DECLARE_CONDITION(condition_title);
DECLARE_CONDITION(condition_pid);
DECLARE_CONDITION(condition_maxage);
DECLARE_CONDITION(condition_windowtype);
DECLARE_CONDITION(condition_windowrole);

/// CONSEQUENCES ///
#define DECLARE_CONSEQUENCE(NAME)                           \
static void NAME(HSConsequence* cons, HSClient* client,     \
                     HSClientChanges* changes)

DECLARE_CONSEQUENCE(consequence_tag);
DECLARE_CONSEQUENCE(consequence_focus);
DECLARE_CONSEQUENCE(consequence_manage);
DECLARE_CONSEQUENCE(consequence_index);
DECLARE_CONSEQUENCE(consequence_pseudotile);
DECLARE_CONSEQUENCE(consequence_fullscreen);
DECLARE_CONSEQUENCE(consequence_switchtag);
DECLARE_CONSEQUENCE(consequence_ewmhrequests);
DECLARE_CONSEQUENCE(consequence_ewmhnotify);
DECLARE_CONSEQUENCE(consequence_hook);
DECLARE_CONSEQUENCE(consequence_keymask);
DECLARE_CONSEQUENCE(consequence_monitor);

/// GLOBALS ///

static HSConditionType g_condition_types[] = {
    { "class",          condition_class             },
    { "instance",       condition_instance          },
    { "title",          condition_title             },
    { "pid",            condition_pid               },
    { "maxage",         condition_maxage            },
    { "windowtype",     condition_windowtype        },
    { "windowrole",     condition_windowrole        },
};

static int     g_maxage_type; // index of "maxage"
static time_t  g_current_rule_birth_time; // data from rules_apply() to condition_maxage()
static unsigned long long g_rule_label_index; // incremental index of rule label

static HSConsequenceType g_consequence_types[] = {
    { "tag",            consequence_tag             },
    { "index",          consequence_index           },
    { "focus",          consequence_focus           },
    { "switchtag",      consequence_switchtag       },
    { "manage",         consequence_manage          },
    { "pseudotile",     consequence_pseudotile      },
    { "fullscreen",     consequence_fullscreen      },
    { "ewmhrequests",   consequence_ewmhrequests    },
    { "ewmhnotify",     consequence_ewmhnotify      },
    { "hook",           consequence_hook            },
    { "keymask",        consequence_keymask         },
    { "monitor",        consequence_monitor         },
};

static GQueue g_rules = G_QUEUE_INIT; // a list of HSRule* elements

/// FUNCTIONS ///
// RULES //
void rules_init() {
    g_maxage_type = find_condition_type("maxage");
    g_rule_label_index = 0;
}

void rules_destroy() {
    g_queue_foreach(&g_rules, (GFunc)rule_destroy, NULL);
    g_queue_clear(&g_rules);
}

// condition types //
static int find_condition_type(const char* name) {
    const char* cn;
    for (int i = 0; i < LENGTH(g_condition_types); i++) {
        cn = g_condition_types[i].name;
        if (!cn) break;
        if (!strcmp(cn, name)) {
            return i;
        }
    }
    return -1;
}

HSCondition* condition_create(int type, char op, char* value, GString* output) {
    HSCondition cond;
    if (op != '=' && type == g_maxage_type) {
        g_string_append_printf(output,
            "rule: Condition maxage only supports the = operator\n");
        return NULL;
    }
    switch (op) {
        case '=': {
            if (type == g_maxage_type) {
                cond.value_type = CONDITION_VALUE_TYPE_INTEGER;
                if (1 != sscanf(value, "%d", &cond.value.integer)) {
                    g_string_append_printf(output,
                        "rule: Can not integer from \"%s\"\n", value);
                    return NULL;
                }
            } else {
                cond.value_type = CONDITION_VALUE_TYPE_STRING;
                cond.value.str = g_strdup(value);
            }
            break;
        }

        case '~': {
            cond.value_type = CONDITION_VALUE_TYPE_REGEX;
            int status = regcomp(&cond.value.reg.exp, value, REG_EXTENDED);
            if (status != 0) {
                char buf[ERROR_STRING_BUF_SIZE];
                regerror(status, &cond.value.reg.exp, buf, ERROR_STRING_BUF_SIZE);
                g_string_append_printf(output,
                    "rule: Can not parse value \"%s\" from condition \"%s\": \"%s\"\n",
                    value, g_condition_types[type].name, buf);
                return NULL;
            }
            cond.value.reg.str = g_strdup(value);
            break;
        }

        default:
            g_string_append_printf(output,
                "rule: Unknown rule condition operation \"%c\"\n", op);
            return NULL;
            break;
    }

    cond.condition_type = type;
    // move to heap
    HSCondition* ptr = g_new(HSCondition, 1);
    *ptr = cond;
    return ptr;
}

static void condition_destroy(HSCondition* cond) {
    if (!cond) {
        return;
    }
    // free members
    switch(cond->value_type) {
        case CONDITION_VALUE_TYPE_STRING:
            free(cond->value.str);
            break;
        case CONDITION_VALUE_TYPE_REGEX:
            regfree(&cond->value.reg.exp);
            g_free(cond->value.reg.str);
            break;
        default:
            break;
    }

    // free cond itself
    g_free(cond);
}

// consequence types //
static int find_consequence_type(const char* name) {
    const char* cn;
    for (int i = 0; i < LENGTH(g_consequence_types); i++) {
        cn = g_consequence_types[i].name;
        if (!cn) break;
        if (!strcmp(cn, name)) {
            return i;
        }
    }
    return -1;
}

HSConsequence* consequence_create(int type, char op, char* value, GString* output) {
    HSConsequence cons;
    switch (op) {
        case '=':
            cons.value_type = CONSEQUENCE_VALUE_TYPE_STRING;
            cons.value.str = g_strdup(value);
            break;

        default:
            g_string_append_printf(output,
                "rule: Unknown rule consequence operation \"%c\"\n", op);
            return NULL;
            break;
    }

    cons.type = type;
    // move to heap
    HSConsequence* ptr = g_new(HSConsequence, 1);
    *ptr = cons;
    return ptr;
}

static void consequence_destroy(HSConsequence* cons) {
    switch (cons->value_type) {
        case CONSEQUENCE_VALUE_TYPE_STRING:
            g_free(cons->value.str);
            break;
    }
    g_free(cons);
}

static bool rule_label_replace(HSRule* rule, char op, char* value, GString* output) {
    switch (op) {
        case '=':
            if (*value == '\0') {
                g_string_append_printf(output,
                    "rule: Rule label cannot be empty");
                return false;
                break;
            }
            g_free(rule->label);
            rule->label = g_strdup(value);
            break;
        default:
            g_string_append_printf(output,
                "rule: Unknown rule label operation \"%c\"\n", op);
            return false;
            break;
    }
    return true;
}

// rules parsing //

HSRule* rule_create() {
    HSRule* rule = g_new0(HSRule, 1);
    rule->once = false;
    rule->birth_time = get_monotonic_timestamp();
    // Add name. Defaults to index number.
    rule->label = g_strdup_printf("%llu", g_rule_label_index++);
    return rule;
}

void rule_destroy(HSRule* rule) {
    // free conditions
    for (int i = 0; i < rule->condition_count; i++) {
        condition_destroy(rule->conditions[i]);
    }
    g_free(rule->conditions);
    // free consequences
    for (int i = 0; i < rule->consequence_count; i++) {
        consequence_destroy(rule->consequences[i]);
    }
    g_free(rule->consequences);
    // free label
    g_free(rule->label);
    // free rule itself
    g_free(rule);
}

void rule_complete(int argc, char** argv, int pos, GString* output) {
    const char* needle = (pos < argc) ? argv[pos] : "";
    GString* buf = g_string_sized_new(20);

    // complete against conditions
    for (int i = 0; i < LENGTH(g_condition_types); i++) {
        g_string_printf(buf, "%s=", g_condition_types[i].name);
        try_complete_partial(needle, buf->str, output);
        g_string_printf(buf, "%s~", g_condition_types[i].name);
        try_complete_partial(needle, buf->str, output);
    }

    // complete against consequences
    for (int i = 0; i < LENGTH(g_consequence_types); i++) {
        g_string_printf(buf, "%s=", g_consequence_types[i].name);
        try_complete_partial(needle, buf->str, output);
    }

    // complete label
    try_complete_partial(needle, "label=", output);
    // complete flags
    try_complete(needle, "prepend", output);
    try_complete(needle, "once",    output);
    try_complete(needle, "not",     output);
    try_complete(needle, "!",       output);
    try_complete(needle, "printlabel", output);

    g_string_free(buf, true);
}

// Compares the id of two rules.
static gint rule_compare_label(const HSRule* a, const HSRule* b) {
    return strcmp(a->label, b->label);
}

// Looks up rules of a given label and removes them from the queue
static bool rule_find_pop(char* label) {
    GList* rule = { NULL };
    bool status = false; // Will be returned as true if any is found
    HSRule rule_find = { 0 };
    rule_find.label = label;
    while ((rule = g_queue_find_custom(&g_rules, &rule_find,
                        (GCompareFunc)rule_compare_label))) {
        // Check if rule with label exists
        if ( rule == NULL ) {
            break;
        }
        status = true;
        // If so, clear data
        rule_destroy((HSRule*)rule->data);
        // Remove and free empty link
        g_queue_delete_link(&g_rules, rule);
    }
    return status;
}

// List all rules in queue
static void rule_print_append_output(HSRule* rule, GString* output) {
    g_string_append_printf(output, "label=%s\t", rule->label);
    // Append conditions
    for (int i = 0; i < rule->condition_count; i++) {
        if (rule->conditions[i]->negated) { // Include flag if negated
            g_string_append_printf(output, "not\t");
        }
        g_string_append_printf(output, "%s=",
            g_condition_types[rule->conditions[i]->condition_type].name);
        switch (rule->conditions[i]->value_type) {
            case CONDITION_VALUE_TYPE_STRING:
                g_string_append_printf(output, "%s\t",
                    rule->conditions[i]->value.str);
                break;
            case CONDITION_VALUE_TYPE_REGEX:
                g_string_append_printf(output, "%s\t",
                    rule->conditions[i]->value.reg.str);
                break;
            default: /* CONDITION_VALUE_TYPE_INTEGER: */
                g_string_append_printf(output, "%i\t",
                    rule->conditions[i]->value.integer);
                break;
        }
    }
    // Append consequences
    for (int i = 0; i < rule->consequence_count; i++) {
        g_string_append_printf(output, "%s=%s\t",
            g_consequence_types[rule->consequences[i]->type].name,
            rule->consequences[i]->value.str);
    }
    // Print new line
    g_string_append_c(output, '\n');
}

int rule_print_all_command(int argc, char** argv, GString* output) {
    // Print entry for each in the queue
    g_queue_foreach(&g_rules, (GFunc)rule_print_append_output, output);
    return 0;
}

// parses an arg like NAME=VALUE to res_name, res_operation and res_value
bool tokenize_arg(char* condition,
                  char** res_name, char* res_operation, char** res_value) {
    // ignore two leading dashes
    if (condition[0] == '-' && condition[1] == '-') {
        condition += 2;
    }

    // get name
    *res_name = condition;


    // locate operation
    char* op = strpbrk(condition, "=~");
    if (!op) {
        return false;
    }
    *res_operation = *op;
    *op = '\0'; // separate string at operation char

    // value is second one (starting after op character)
    *res_value = op + 1;
    return true;
}

static void rule_add_condition(HSRule* rule, HSCondition* cond) {
    rule->conditions = g_renew(HSCondition*,
                               rule->conditions, rule->condition_count + 1);
    rule->conditions[rule->condition_count] = cond;
    rule->condition_count++;
}

static void rule_add_consequence(HSRule* rule, HSConsequence* cons) {
    rule->consequences = g_renew(HSConsequence*,
                               rule->consequences, rule->consequence_count + 1);
    rule->consequences[rule->consequence_count] = cons;
    rule->consequence_count++;
}


int rule_add_command(int argc, char** argv, GString* output) {
    // usage: rule COND=VAL ... then

    if (argc < 2) {
        return HERBST_NEED_MORE_ARGS;
    }
    // temporary data structures
    HSRule* rule = rule_create();
    HSCondition* cond;
    HSConsequence* cons;
    bool printlabel = false;
    bool negated = false;
    bool prepend = false;
    struct {
        const char* name;
        bool* flag;
    } flags[] = {
        { "prepend",&prepend },
        { "not",    &negated },
        { "!",      &negated },
        { "once",   &rule->once },
        { "printlabel",&printlabel },
    };

    // parse rule incrementally. always maintain a correct rule in rule
    while (SHIFT(argc, argv)) {
        char* name;
        char* value;
        char op;

        // is it a consequence or a condition?
        bool consorcond = tokenize_arg(*argv, &name, &op, &value);
        int type;
        bool flag_found = false;
        int flag_index = -1;

        for (int i = 0; i < LENGTH(flags); i++) {
            if (!strcmp(flags[i].name, name)) {
                flag_found = true;
                flag_index = i;
                break;
            }
        }

        if (flag_found) {
            *flags[flag_index].flag = ! *flags[flag_index].flag;
        }

        else if (consorcond && (type = find_condition_type(name)) >= 0) {
            cond = condition_create(type, op, value, output);
            if (!cond) {
                rule_destroy(rule);
                return HERBST_INVALID_ARGUMENT;
            }
            cond->negated = negated;
            negated = false;
            rule_add_condition(rule, cond);
        }

        else if (consorcond && (type = find_consequence_type(name)) >= 0) {
            cons = consequence_create(type, op, value, output);
            if (!cons) {
                rule_destroy(rule);
                return HERBST_INVALID_ARGUMENT;
            }
            rule_add_consequence(rule, cons);
        }

        // Check for a provided label, and replace default index if so
        else if (consorcond && (!strcmp(name,"label"))) {
            if (!rule_label_replace(rule, op, value, output)) {
                rule_destroy(rule);
                return HERBST_INVALID_ARGUMENT;
            }
        }

        else {
            // need to hardcode "rule:" here because args are shifted
            g_string_append_printf(output,
                "rule: Unknown argument \"%s\"\n", *argv);
            rule_destroy(rule);
            return HERBST_INVALID_ARGUMENT;
        }
    }

    if (printlabel) {
       g_string_append_printf(output, "%s\n", rule->label);
    }

    if (prepend) g_queue_push_head(&g_rules, rule);
    else         g_queue_push_tail(&g_rules, rule);
    return 0;
}

void complete_against_rule_names(int argc, char** argv, int pos, GString* output) {
    const char* needle;
    if (pos >= argc) {
        needle = "";
    } else {
        needle = argv[pos];
    }
    // Complete labels
    GList* cur_rule = g_queue_peek_head_link(&g_rules);
    while (cur_rule != NULL) {
        try_complete(needle, ((HSRule*)cur_rule->data)->label, output);
        cur_rule = g_list_next(cur_rule);
    }
}


int rule_remove_command(int argc, char** argv, GString* output) {
    if (argc < 2) {
        return HERBST_NEED_MORE_ARGS;
    }

    if (!strcmp(argv[1], "--all") || !strcmp(argv[1], "-F")) {
        // remove all rules
        g_queue_foreach(&g_rules, (GFunc)rule_destroy, NULL);
        g_queue_clear(&g_rules);
        g_rule_label_index = 0;
        return 0;
    }

    // Deletes rule with given label
    if (!rule_find_pop(argv[1])) {
        g_string_append_printf(output, "Couldn't find rule: \"%s\"", argv[1]);
        return HERBST_INVALID_ARGUMENT;
    }
    return 0;
}

// rules applying //
void client_changes_init(HSClientChanges* changes, HSClient* client) {
    memset(changes, 0, sizeof(HSClientChanges));
    changes->tree_index = g_string_new("");
    changes->focus = false;
    changes->switchtag = false;
    changes->manage = true;
    changes->fullscreen = ewmh_is_fullscreen_set(client->window);
    changes->keymask = g_string_new("");
}

void client_changes_free_members(HSClientChanges* changes) {
    if (!changes) return;
    if (changes->tag_name) {
        g_string_free(changes->tag_name, true);
    }
    if (changes->tree_index) {
        g_string_free(changes->tree_index, true);
    }
    if (changes->monitor_name) {
        g_string_free(changes->monitor_name, true);
    }
}

// apply all rules to a certain client an save changes
void rules_apply(HSClient* client, HSClientChanges* changes) {
    GList* cur = g_rules.head;
    while (cur) {
        HSRule* rule = (HSRule*)cur->data;
        bool matches = true;    // if current condition matches
        bool rule_match = true; // if entire rule matches
        bool rule_expired = false;
        g_current_rule_birth_time = rule->birth_time;

        // check all conditions
        for (int i = 0; i < rule->condition_count; i++) {
            int type = rule->conditions[i]->condition_type;

            if (!rule_match && type != g_maxage_type) {
                // implement lazy AND &&
                // ... except for maxage
                continue;
            }

            matches = g_condition_types[type].
                matches(rule->conditions[i], client);

            if (!matches && !rule->conditions[i]->negated
                && rule->conditions[i]->condition_type == g_maxage_type) {
                // if if not negated maxage does not match anymore
                // then it will never match again in the future
                rule_expired = true;
            }

            if (rule->conditions[i]->negated) {
                matches = ! matches;
            }
            rule_match = rule_match && matches;
        }

        if (rule_match) {
            // apply all consequences
            for (int i = 0; i < rule->consequence_count; i++) {
                int type = rule->consequences[i]->type;
                g_consequence_types[type].
                    apply(rule->consequences[i], client, changes);
            }

        }

        // remove it if not wanted or needed anymore
        if ((rule_match && rule->once) || rule_expired) {
            GList* next = cur->next;
            rule_destroy((HSRule*)cur->data);
            g_queue_remove_element(&g_rules, cur);
            cur = next;
            continue;
        }

        // try next
        cur = cur ? cur->next : NULL;
    }
}

/// CONDITIONS ///
static bool condition_string(HSCondition* rule, const char* string) {
    if (!rule || !string) {
        return false;
    }

    int status;
    regmatch_t match;
    int int_value;
    switch (rule->value_type) {
        case CONDITION_VALUE_TYPE_STRING:
            return !strcmp(string, rule->value.str);
            break;
        case CONDITION_VALUE_TYPE_REGEX:
            status = regexec(&rule->value.reg.exp, string, 1, &match, 0);
            // only accept it, if it matches the entire string
            if (status == 0
                && match.rm_so == 0
                && match.rm_eo == strlen(string)) {
                return true;
            } else {
                return false;
            }
            break;
        case CONDITION_VALUE_TYPE_INTEGER:
            return (1 == sscanf(string, "%d", &int_value)
                && int_value == rule->value.integer);
            break;
    }
    return false;
}

static bool condition_class(HSCondition* rule, HSClient* client) {
    GString* window_class = window_class_to_g_string(g_display, client->window);
    bool match = condition_string(rule, window_class->str);
    g_string_free(window_class, true);
    return match;
}

static bool condition_instance(HSCondition* rule, HSClient* client) {
    GString* inst = window_instance_to_g_string(g_display, client->window);
    bool match = condition_string(rule, inst->str);
    g_string_free(inst, true);
    return match;
}

static bool condition_title(HSCondition* rule, HSClient* client) {
    return condition_string(rule, client->title->str);
}

static bool condition_pid(HSCondition* rule, HSClient* client) {
    if (client->pid < 0) {
        return false;
    }
    if (rule->value_type == CONDITION_VALUE_TYPE_INTEGER) {
        return rule->value.integer == client->pid;
    } else {
        char buf[1000]; // 1kb ought to be enough for every int
        sprintf(buf, "%d", client->pid);
        return condition_string(rule, buf);
    }
}

static bool condition_maxage(HSCondition* rule, HSClient* client) {
    time_t diff = get_monotonic_timestamp() - g_current_rule_birth_time;
    return (rule->value.integer >= diff);
}

static bool condition_windowtype(HSCondition* rule, HSClient* client) {
    int windowtype = ewmh_get_window_type(client->window);
    if (windowtype < 0) {
        return false;
    } else {
        // if found, then treat the window type as a string value,
        // which is registered in g_netatom_names[]
        return condition_string(rule, g_netatom_names[windowtype]);
    }
    return false;
}

static bool condition_windowrole(HSCondition* rule, HSClient* client) {
    GString* role = window_property_to_g_string(g_display, client->window,
        ATOM("WM_WINDOW_ROLE"));
    if (!role) return false;
    bool match = condition_string(rule, role->str);
    g_string_free(role, true);
    return match;
}

/// CONSEQUENCES ///
void consequence_tag(HSConsequence* cons,
                     HSClient* client, HSClientChanges* changes) {
    if (changes->tag_name) {
        g_string_assign(changes->tag_name, cons->value.str);
    } else {
        changes->tag_name = g_string_new(cons->value.str);
    }
}

void consequence_focus(HSConsequence* cons, HSClient* client,
                       HSClientChanges* changes) {
    changes->focus = string_to_bool(cons->value.str, changes->focus);
}

void consequence_manage(HSConsequence* cons, HSClient* client,
                        HSClientChanges* changes) {
    changes->manage = string_to_bool(cons->value.str, changes->manage);
}

void consequence_index(HSConsequence* cons, HSClient* client,
                               HSClientChanges* changes) {
    g_string_assign(changes->tree_index, cons->value.str);
}

void consequence_pseudotile(HSConsequence* cons, HSClient* client,
                            HSClientChanges* changes) {
    client->pseudotile = string_to_bool(cons->value.str, client->pseudotile);
}

void consequence_fullscreen(HSConsequence* cons, HSClient* client,
                            HSClientChanges* changes) {
    changes->fullscreen = string_to_bool(cons->value.str, changes->fullscreen);
}

void consequence_switchtag(HSConsequence* cons, HSClient* client,
                           HSClientChanges* changes) {
    changes->switchtag = string_to_bool(cons->value.str, changes->switchtag);
}

void consequence_ewmhrequests(HSConsequence* cons, HSClient* client,
                              HSClientChanges* changes) {
    // this is only a flag that is unused during initialization (during
    // manage()) and so can be directly changed in the client
    client->ewmhrequests = string_to_bool(cons->value.str, client->ewmhrequests);
}

void consequence_ewmhnotify(HSConsequence* cons, HSClient* client,
                            HSClientChanges* changes) {
    client->ewmhnotify = string_to_bool(cons->value.str, client->ewmhnotify);
}

void consequence_hook(HSConsequence* cons, HSClient* client,
                            HSClientChanges* changes) {
    GString* winid = g_string_sized_new(20);
    g_string_printf(winid, "0x%lx", client->window);
    const char* hook_str[] = { "rule" , cons->value.str, winid->str };
    hook_emit(LENGTH(hook_str), hook_str);
    g_string_free(winid, true);
}

void consequence_keymask(HSConsequence* cons,
                         HSClient* client, HSClientChanges* changes) {
    if (changes->keymask) {
        g_string_assign(changes->keymask, cons->value.str);
    } else {
        changes->keymask = g_string_new(cons->value.str);
    }
}

void consequence_monitor(HSConsequence* cons, HSClient* client,
                            HSClientChanges* changes) {
    if (changes->monitor_name) {
        g_string_assign(changes->monitor_name, cons->value.str);
    } else {
        changes->monitor_name = g_string_new(cons->value.str);
    }
}