/*
 * 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"

static struct trie *trie_base;

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 bool trie_set_deep(char string[], int64_t val, struct trie *vertex) {
	// Recursive function to find and set a value
	if (string[0] = '\0') {
		vertex -> val = val;
		vertex -> defined = true;
		return true;
	} else {
		int chld_index = indexof(string[0]);
		if (chld_index == -1) {
			return false; //and don't save anything
		} else if (vertex -> children[chld_index] == NULL) {
			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 false;
			}
		}
		return trie_set_deep(string+1, val, vertex->children[chld_index]);
	}
}

bool trie_set(char string[], int64_t val) {
	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;
		}
	}
	return trie_set_deep(string, val, trie_base);
}

static struct trie_retval trie_lookup_deep(char string[], struct trie *vertex) {
	if (string[0] == '\0') {
		return (struct trie_retval) {vertex -> val, vertex -> defined};
	} else {
		int chld_index = indexof(string[0]);
		if (chld_index == -1 || vertex -> children[chld_index] == NULL) {
			return (struct trie_retval) {0, false};
		} else {
			return trie_lookup_deep(string + 1, vertex->children[chld_index]);
		}
	}
}

struct trie_retval trie_lookup(char string[]) {
	if (trie_base == NULL) {
		return (struct trie_retval) {0, false};
	} else return trie_lookup_deep(string, trie_base);
}

bool trie_load(void) {
	FILE *f = fopen(cfg_trie_file, "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 %d\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 = %d", name, val);
		}
	}
	return true;
}

static bool trie_dfs(char prefix[], int prefixlen, FILE *f, struct trie *vertex) {
	if (vertex == NULL) {// Very special case;
		return true;
	} else {
		bool retval = true;
		if (vertex -> defined) {
			prefix[prefixlen] = '\0';
			fprintf(f, "%s %d\n", prefix, vertex -> val);
		}
		for (int i = 0; i<37; i++) {
			if (vertex -> children[i] != NULL) {
				prefix[prefixlen] = charof(i);
				retval &= trie_dfs(prefix, prefixlen + 1, f, vertex -> children[i]);
			}
		}
		return retval;
	}
}

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

	// DFS, write every found variable into f
	char prefix[cfg_var_name_max_len +1];
	prefix[cfg_var_name_max_len +1] = '\0';
	int prefixlen = 0;

	return trie_dfs(prefix, prefixlen, f, trie_base);
}