/*
 * trie.c: Trie implementation for storing values
 */

#include <string.h>
#include <syslog.h>
#include <stdio.h>
#include <stdlib.h>

#include "trie.h"
#include "config.h"
#include "task.h"

enum dfs_list {
	VERTICES, VARIABLES
};

static struct trie *trie_base = NULL;

static int indexof(char c) {
	// ASCII only!
	if ('A' <= c && c <= 'Z') {
		return (c - 'A');
	} else if ('0' <= c && c <= '9') {
		return (c - '0' + 26);
	} else if (c == '_') {
		return 36;
	} else {
		// Something weird happened
		syslog(cfg_log_facility|LOG_NOTICE, "trie: weird character: %c", c);
		return -1;
	}
}

static char charof(int i) {
	//ASCII again
	if (i <= 25){
		return ('A' + i);
	} else if (26 <= i && i <= 35) {
		return ('0' + i - 26);
	} else if (i == 36) {
		return '_';
	} else {
		syslog(cfg_log_facility|LOG_NOTICE, "trie: weird character index: %d", i);
		return '\0';
	}
}

static struct trie *trie_find_vertex(char string[], struct trie *vertex, bool create) {
	if (vertex == NULL) {
		if (create == false) {
			return NULL;
		} else {
			vertex = (struct trie *) calloc(1, sizeof(struct trie));
			if (vertex  == NULL) {
				syslog(cfg_log_facility | LOG_ERR, "trie: could not allocate space: %m");
				return NULL;
			}
		}
	}
	if (string[0] == '\0') {
		return vertex;
	} else {
		int chld_index = indexof(string[0]);
		if (chld_index == -1) {
			return NULL;
		} else if (vertex -> children[chld_index] == NULL) {
			if (create == false) {
				return NULL;
			} else {
				vertex -> children[chld_index] = (struct trie *) calloc(1, sizeof(struct trie));
				if (vertex -> children[chld_index] == NULL) {
					syslog(cfg_log_facility | LOG_ERR, "trie: could not allocate space: %m");
					return NULL;
				}
			}
		}
		return trie_find_vertex(string+1, vertex->children[chld_index], create);
	}
}


static bool trie_redefine (char string[], int64_t val, bool def){
	if (trie_base == NULL) {
		trie_base = (struct trie *) calloc(1, sizeof(struct trie));
		if(trie_base == NULL) {
			syslog(cfg_log_facility | LOG_ERR, "trie: could not allocate any space: %m");
			return false;
		}
	}
	struct trie *v = trie_find_vertex(string, trie_base, def);
	if (v == NULL && def == true) {
		//Something is wrong, but it is already logged
		return false;
	} else {
		v -> val = val;
		v -> def = def;
		//Recalculate tasks
		if (v -> tasks != NULL) {
			for (uint64_t i = 0; i < v -> tasks -> elems; i++) {
				if (v -> tasks -> arr[i] != NULL) {
					uint64_t id = *(uint64_t *)(v -> tasks -> arr[i]);
					task_recalc(id);
				}
			}
		}
		return true;
	}
}

bool trie_set(char string[], int64_t val) {
	return trie_redefine(string, val, true);
}
bool trie_unset(char string[]) {
	return trie_redefine(string, 0, false);
}

struct trie_retval trie_lookup(char string[]) {
	struct trie *v = trie_find_vertex(string, trie_base, false);
	if (v == NULL) {
		return (struct trie_retval) {0, false, NULL};
	} else {
		return (struct trie_retval) {v -> val, v -> def, v->tasks};
	}
}

bool trie_load(const char fn[]) {
	FILE *f = fopen(fn, "r");
	if (f == NULL) {
		syslog(cfg_log_facility | LOG_WARNING, "trie: could not load trie from file: %m");
		return false;
	}

	//FIXME: This is bad.
	int64_t val;
	char name[cfg_var_name_max_len+1];
	int status;
	while ((status = fscanf(f, "%s %ld\n", name, &val)) != EOF) {
		if (status != 2) {
			syslog(cfg_log_facility | LOG_ERR, "trie: fscanf matched bad number of items: %d", status);
			return false;
		}
		if(trie_set(name, val) == false) {
			syslog(cfg_log_facility | LOG_WARNING, "trie: setting a variable failed: %s = %ld", name, val);
		}
	}
	return true;
}

static bool trie_dfs(char prefix[], uint64_t prefixlen, struct grow *list, struct trie *vertex, enum dfs_list style) {
	if (vertex == NULL) {// Very special case;
		return true;
	} else {
		bool retval = true;
		if (style == VARIABLES) {
			if (prefixlen > cfg_var_name_max_len) {
				syslog(cfg_log_facility | LOG_NOTICE, "trie: dfs: too long variable name in trie");
				return false;
			}
			if (vertex -> def) {
				prefix[prefixlen] = '\0';
				// Add to list
				struct trie_list *l = malloc(sizeof(struct trie_list));
				if (l == NULL) {
					syslog(cfg_log_facility|LOG_WARNING, "trie: dfs: cannot create list element: %m");
					return false;
				}
				l -> val = vertex -> val;
				l -> name = malloc((prefixlen + 1) * sizeof(char));
				strcpy(l->name, prefix);
				retval &=grow_push(l, list);
			}
		} else if (style == VERTICES) {
			// Add pointers to all vertices
			retval &= grow_push(vertex, list);
		}
		for (int i = 0; i<37; i++) {
			if (vertex -> children[i] != NULL) {
				if (style == VARIABLES) {
					prefix[prefixlen] = charof(i);
				}
				retval &= trie_dfs(prefix, prefixlen + 1, list, vertex -> children[i], style);
			}
		}
		return retval;
	}
}

bool trie_save(const char fn[]) {
	FILE *f = fopen(fn, "w");
	if (f == NULL) {
		syslog(cfg_log_facility | LOG_CRIT, "trie: could not open file to save trie in: %m");
		return false;
	}

	// DFS
	struct grow *list = grow_init(true);
	char prefix[cfg_var_name_max_len +1];
	prefix[cfg_var_name_max_len +1] = '\0';
	trie_dfs(prefix, 0, list, trie_base, VARIABLES);

	for (uint64_t i = 0; i < list -> elems; i++) {
		struct trie_list l = *(struct trie_list *)(list -> arr[i]);
		fprintf(f, "%s %ld\n", l.name, l.val);
	}
	grow_drop(list);
	return true;
}

struct grow *trie_list(void) {
	struct grow *list = grow_init(true);
	char prefix[cfg_var_name_max_len +1];
	prefix[cfg_var_name_max_len +1] = '\0';
	trie_dfs(prefix, 0, list, trie_base, VARIABLES);
	return list;
}

bool trie_assoc(char var[], uint64_t task) {
	struct trie *v = trie_find_vertex(var, trie_base, true);
	if (v == NULL) {
		return false;
	} else {
		if (v -> tasks == NULL) {
			v -> tasks = grow_init(true);
			if (v->tasks == NULL) {
				return false;
			}
		}
		uint64_t *p_task = malloc(sizeof(uint64_t));
		if (p_task == NULL) {
			syslog(cfg_log_facility | LOG_ERR, "trie: Could not associate: %m");
			return false;
		}
		*p_task = task;
		return grow_push(p_task, v->tasks);
	}
}

bool trie_unassoc(char var[], uint64_t task) {
	struct trie *v = trie_find_vertex(var, trie_base, false);
	if (v == NULL) {
		return false; //Was not associated
	} else {
		if (v -> tasks == NULL) {
			return false; //Was not associated
		} else {
			bool retval = false;
			for (uint64_t i = 0; i < v->tasks->elems; i++) {
				uint64_t *t = (uint64_t *)(v->tasks->arr[i]);
				if (t == NULL) {
					continue;
				} else if (*t == task) {
					// Erase it
					v -> tasks -> active_elems--;
					free(t);
					v->tasks->arr[i] = NULL;
					retval = true;
				}
			}
			if (v -> tasks -> active_elems == 0) {
				grow_drop(v->tasks);
			}
			return retval;
		}
	}
}

void trie_drop (void) {
	struct grow *list = grow_init(true);
	trie_dfs("", 0, list, trie_base, VERTICES);
	grow_drop(list);
	return;
}