#include "fileserv.h"
#include <errno.h>
#include <assert.h>
#include <string.h>
#include <time.h>
#include <ctype.h>
#include "dirls.h"
#include "wordsplit.h"

enum tmpl_node_type {
	NODE_TEXT,
	NODE_LOOP,
	NODE_COND,
	NODE_EXPR
};

typedef STAILQ_HEAD(tmpl_node_list, tmpl_node) TMPL_NODE_LIST;

struct tmpl_cond {
	char *expr;
	TMPL_NODE_LIST branch[2];
};
						 
struct tmpl_node {
	int type;
	STAILQ_ENTRY(tmpl_node) next;
	union {
		char *text;
		struct tmpl_node_list loop;
		struct tmpl_cond cond;
	} v;
};

typedef struct tmpl_node TMPL_NODE;

struct condition {
	TMPL_NODE *node;
	int brn;
	STAILQ_ENTRY(condition) next;
};
typedef STAILQ_HEAD(, condition) COND_LIST;

struct eval_env;

/* Type-agnostic node functions */

struct node_class {
	void (*node_init)(TMPL_NODE *);
	void (*node_free)(TMPL_NODE *);
	int (*node_eval)(TMPL_NODE *, struct eval_env *);
};

static int node_text_eval(TMPL_NODE *, struct eval_env *);
static int node_loop_eval(TMPL_NODE *, struct eval_env *);
static int node_cond_eval(TMPL_NODE *, struct eval_env *);
static int node_expr_eval(TMPL_NODE *, struct eval_env *);

static void node_loop_init(TMPL_NODE *);
static void node_loop_free(TMPL_NODE *);

static void node_cond_init(TMPL_NODE *);
static void node_cond_free(TMPL_NODE *);

static struct node_class node_class[] = {
	[NODE_TEXT] = { NULL, NULL, node_text_eval },
	[NODE_LOOP] = { node_loop_init, node_loop_free, node_loop_eval },
	[NODE_COND] = { node_cond_init, node_cond_free, node_cond_eval },
	[NODE_EXPR] = { NULL, NULL, node_expr_eval }
};

#define ASSERT_NODE_TYPE(n) \
	assert((n)->type >= 0 && (n)->type <= sizeof(node_class)/sizeof(node_class[0]))

static void
node_init(TMPL_NODE *node)
{
	ASSERT_NODE_TYPE(node);
	if (node_class[node->type].node_init)
		return node_class[node->type].node_init(node);
}

static void
node_free(TMPL_NODE *node)
{
	ASSERT_NODE_TYPE(node);
	if (node_class[node->type].node_free)
		node_class[node->type].node_free(node);
	free(node);
}

static int
node_eval(TMPL_NODE *node, struct eval_env *env)
{
	ASSERT_NODE_TYPE(node);
	assert(node_class[node->type].node_eval);
	return node_class[node->type].node_eval(node, env);
}


/* Node list functions */

static void
node_list_free(TMPL_NODE_LIST *nlist)
{
	TMPL_NODE *node;

	while ((node = STAILQ_FIRST(nlist))) {
		STAILQ_REMOVE_HEAD(nlist, next);
		node_free(node);
	}
}

static int
node_list_eval(TMPL_NODE_LIST *nlist, struct eval_env *env)
{
	TMPL_NODE *node;
	int rc = 0;
	
	STAILQ_FOREACH(node, nlist, next) {
		rc = node_eval(node, env);
		if (rc)
			break;
	}
	return rc;
}

/* Node-specific initialization and deallocation functions */
static void
node_loop_init(TMPL_NODE *node)
{
	STAILQ_INIT(&node->v.loop);
}

static void
node_loop_free(TMPL_NODE *node)
{
	node_list_free(&node->v.loop);
}

static void
node_cond_init(TMPL_NODE *node)
{
	STAILQ_INIT(&node->v.cond.branch[0]);
	STAILQ_INIT(&node->v.cond.branch[1]);
}

static void
node_cond_free(TMPL_NODE *node)
{
	node_list_free(&node->v.cond.branch[0]);
	node_list_free(&node->v.cond.branch[1]);
}

/* Parser error codes */
enum template_error {
	TMPL_NOERR,
	TMPL_ERR_LOOP_NESTING,
	TMPL_ERR_ENDLOOP_WITHOUT_LOOP,
	TMPL_ERR_ENDIF_WITHOUT_IF,
	TMPL_ERR_ELSE_WITHOUT_IF,
	TMPL_ERR_DUP_ELSE,
	TMPL_ERR_ESCAPE_NOT_CLOSED,
	TMPL_ERR_LOOP_NOT_CLOSED,
	TMPL_ERR_COND_NOT_CLOSED,
	TMPL_ERR_NOMEM
};

/* Corresponding textual descriptions */
static char const *tmpl_err_str[] =  {
	"no error",
	"attempt to nest loops",
	"endloop without loop",
	"endif without if",
	"else without if",
	"duplicate else",
	"escape not closed",
	"loop not closed",
	"conditional not closed",
	"not enough memory"
};

/* Template parser state */
typedef struct template_parser_state {
	int escape:1;       /* True if in a {% %} construct */
	int loop:1;         /* True if within a loop / endloop block */
	COND_LIST cond;     /* Stack of nested conditionals */
	char const *start;  /* Start of text fragment being parsed */
	char const *cur;    /* Current position in the text */
	int error;          /* Error state */      
} TEMPLATE_PARSER_STATE;

/* Allocate and initialize single node */
static inline TMPL_NODE *
node_alloc(TEMPLATE_PARSER_STATE *st, int type, size_t extra)
{
	TMPL_NODE *np = calloc(1, sizeof(*np) + extra);
	if (np)
		np->type = type;
	else
		st->error = TMPL_ERR_NOMEM;
	node_init(np);
	return np;
}

/* Template parser */
static void parse_template(TMPL_NODE_LIST *nodes, TEMPLATE_PARSER_STATE *st);

static TMPL_NODE *
new_text_node(TEMPLATE_PARSER_STATE *st, int type, size_t len)
{
	TMPL_NODE *np = node_alloc(st, type, len + 1);
	if (np) {
		np->v.text = (char*)(np + 1);
		memcpy(np->v.text, st->start, len);
		np->v.text[len] = 0;
	}
	return np;
}

static TMPL_NODE *
next_text_node(TEMPLATE_PARSER_STATE *st)
{
	st->start = st->cur;
	while (*st->cur) {
		if (*st->cur == '{' && st->cur[1] == '%') {
			st->escape = 1;
			break;
		}
		st->cur++;
	}

	return new_text_node(st, NODE_TEXT, st->cur - st->start);
}

static TMPL_NODE *
parse_cond(TEMPLATE_PARSER_STATE *st, int brn, size_t off, size_t len)
{
	struct condition cond;
	TMPL_NODE *np;

	while (off < len && isspace(st->start[off]))
		off++;
	len -= off;
	
	np = node_alloc(st, NODE_COND, len + 1);
	if (np) {
		np->v.cond.expr = (char*)(np + 1);
		memcpy(np->v.cond.expr, st->start + off, len);
		np->v.cond.expr[len] = 0;
		
		cond.node = np;
		cond.brn = brn;
		STAILQ_INSERT_HEAD(&st->cond, &cond, next);
		STAILQ_INIT(&np->v.cond.branch[!cond.brn]);
		parse_template(&np->v.cond.branch[cond.brn], st);
	}
	return np;
}

static TMPL_NODE *
next_escape_node(TEMPLATE_PARSER_STATE *st)
{
	size_t len;
	
	st->start = st->cur + 2;
	while (*st->cur) {
		if (*st->cur == '%' && st->cur[1] == '}') {
			st->escape = 0;
			break;
		}
		st->cur++;
	}

	if (st->escape) {
		st->escape = 0;
		return new_text_node(st, NODE_TEXT, st->cur - st->start);
	}
	
	while (st->start < st->cur && isspace(st->start[0]))
		st->start++;

	len = st->cur - st->start;
	while (len > 0 && isspace(st->start[len-1]))
		len--;

	st->cur += 2;

	if (memcmp(st->start, "loop", len) == 0) {
		TMPL_NODE *np;

		if (st->loop) {
			st->error = TMPL_ERR_LOOP_NESTING;
			return NULL;
		}
		st->loop = 1;
		np = node_alloc(st, NODE_LOOP, 0);
		if (np)
			parse_template(&np->v.loop, st);
		return np;
	}

	if (memcmp(st->start, "endloop", len) == 0) {
		if (!st->loop) {
			st->error = TMPL_ERR_ENDLOOP_WITHOUT_LOOP;
			return NULL;
		}
		st->loop = 0;
		return NULL;
	}

	if (len > 2
	    && (memcmp(st->start, "if", 2) == 0	&& isspace(st->start[2]))) 
		return parse_cond(st, 1, 2, len);

	if (len > 6
	    && (memcmp(st->start, "unless", 6) == 0 && isspace(st->start[6])))
		return parse_cond(st, 0, 6, len);
		
	if (memcmp(st->start, "endif", len) == 0) {
		if (STAILQ_FIRST(&st->cond))
			STAILQ_REMOVE_HEAD(&st->cond, next);
		else
			st->error = TMPL_ERR_ENDIF_WITHOUT_IF;
		return NULL;
	}
	    

	if (memcmp(st->start, "else", len) == 0) {
		TMPL_NODE *np;
		struct condition *cond = STAILQ_FIRST(&st->cond);
		if (!cond) {
			st->error = TMPL_ERR_ELSE_WITHOUT_IF;
			return NULL;
		}
		np = cond->node;
		if (STAILQ_FIRST(&np->v.cond.branch[!cond->brn])) {
			st->error = TMPL_ERR_DUP_ELSE;
			return NULL;
		}
		parse_template(&np->v.cond.branch[!cond->brn], st);
		return NULL;
	}
	
	return new_text_node(st, NODE_EXPR, len);
}

static TMPL_NODE *
next_node(TEMPLATE_PARSER_STATE *st)
{
	if (st->error)
		return NULL;
	if (*st->cur == 0)
		return NULL;
	return (st->escape ? next_escape_node : next_text_node)(st);
}
	
static void
parse_template(TMPL_NODE_LIST *nodes, TEMPLATE_PARSER_STATE *st)
{
	TMPL_NODE *np;
	
	STAILQ_INIT(nodes);
	
	while ((np = next_node(st)))
		STAILQ_INSERT_TAIL(nodes, np, next);
}

TMPL_NODE_LIST node_list = STAILQ_HEAD_INITIALIZER(node_list);
/* index_disabled inhibits creation of directory indexes. It is set only
   if the built-in index template cannot be compiled and the custom template
   was not supplied or failed to compile too. */
static int index_disabled;

int
parse_template_string(char const *str)
{
	TEMPLATE_PARSER_STATE state;

	state.escape = 0;
	state.loop = 0;
	STAILQ_INIT(&state.cond);
	state.start = str;
	state.cur = str;
	state.error = TMPL_NOERR;

	parse_template(&node_list, &state);

	if (state.error != TMPL_NOERR) {
		error("error parsing template near character %d: %s",
		      state.start - str, 
		      tmpl_err_str[state.error]);
		node_list_free(&node_list);
		return -1;
	}

	if (state.escape)
		state.error = TMPL_ERR_ESCAPE_NOT_CLOSED;
	else if (state.loop)
		state.error = TMPL_ERR_LOOP_NOT_CLOSED;
	else if (STAILQ_FIRST(&state.cond))
		state.error = TMPL_ERR_COND_NOT_CLOSED;
	
	if (state.error != TMPL_NOERR) {
		error("error parsing template (at end): %s",
		      tmpl_err_str[state.error]);
		node_list_free(&node_list);
		return -1;
	}

	return 0;
}
	
int
parse_template_file(char const *file_name)
{
	struct stat st;
	char *buf;
	FILE *fp;
	ssize_t n;
	int rc;
	
	if (stat(file_name, &st)) {
		error("can't stat %s: %s", file_name, strerror(errno));
		return -1;
	}
	fp = fopen(file_name, "r");
	if (!fp) {
		error("can't open %s: %s", file_name, strerror(errno));
		return -1;
	}
		
	buf = malloc(st.st_size + 1);
	if (!buf) {
		error("can't open %s: %s", file_name, strerror(errno));
		fclose(fp);
		return -1;
	}
		
	n = fread(buf, st.st_size, 1, fp);
	if (n == 1) {
		buf[st.st_size] = 0;
		rc = parse_template_string(buf);
	} else {
		error("error reading from %s: %s", file_name, strerror(errno));
		rc = 1;
	}
	fclose(fp);
	free(buf);
	return rc;
}

/* Directory tmpl scanner */

/* Run-time template evaluator */
typedef struct eval_env {
	int fd;                /* Output file descriptor */
	CONFIG const *conf;    /* Associated configuration settings */
	DIRLSENT *ent;         /* Current listing entry */
	int n;                 /* Ordinal number of the entry in the listing */
	ICON const *icon;      /* Icon associated with the entry */
	struct wordsplit ws;   /* Word-splitter tool */
	int wsflags;           /* Its flags */
	INDEX_SORT_COL col;    /* Sorting column */
	INDEX_SORT_ORD ord;    /* Sorting order */
#define expansion ws.ws_wordv[0]
} EVAL_ENV;

static int
eval_expand(char const *str, EVAL_ENV *env)
{
	if (wordsplit(str, &env->ws, env->wsflags)) 
		return -1;
	env->wsflags |= WRDSF_REUSE;
	return 0;
}

static int
node_text_eval(TMPL_NODE *node, EVAL_ENV *env)
{
	size_t len = strlen(node->v.text);
	ssize_t n = write(env->fd, node->v.text, len);
	if (n != len) {
		if (n == -1)
			error("tmpl write error: %s", strerror(errno));
		else
			error("tmpl write error: %s", "disk full?");
		return -1;
	}
	return 0;
}

static int
node_expr_eval(TMPL_NODE *node, EVAL_ENV *env)	
{
	size_t len;
	ssize_t n;
	
	if (eval_expand(node->v.text, env)) 
		return -1;
	len = strlen(env->expansion);
	n = write(env->fd, env->expansion, len);
	if (n != len) {
		if (n == -1)
			error("tmpl write error: %s", strerror(errno));
		else
			error("tmpl write error: %s", "disk full?");
		return -1;
	}
	return 0;
}

static int
node_cond_eval(TMPL_NODE *node, EVAL_ENV *env)
{
	if (eval_expand(node->v.cond.expr, env)) 
		return -1;
	return node_list_eval(&node->v.cond.branch[env->expansion[0] != 0],
			      env);
}

static int
node_loop_eval(TMPL_NODE *node, EVAL_ENV *env)
{
	while (env->ent) {
		if (node_list_eval(&node->v.loop, env))
			return -1;
		env->ent = STAILQ_NEXT(env->ent, next);
		env->n++;
	}
	return 0;
}

static inline int
streq(const char *v, const char *s, size_t l)
{
	return strncmp(v, s, l) == 0 && v[l] == 0;
}

static inline int
retstr(char **ret, char const *str)
{
	*ret = strdup(str);
	return *ret ? WRDSE_OK : WRDSE_NOSPACE;
}

static int
exp_rowclass(char **ret, EVAL_ENV *env)
{
	return retstr(ret, env->n % 2 ? "odd" : "even");
}

static int
exp_filename(char **ret, EVAL_ENV *env)
{
	if (env->ent)
		return retstr(ret, env->ent->name);
	else
		return WRDSE_UNDEF;
}

static int
exp_filesize(char **ret, EVAL_ENV *env)
{
	if (env->ent) {
		char const *suf[] = { "", "K", "M", "G", "T" };
		int i;
		double s = env->ent->st.st_size;
		char buf[80];
		
		for (i = 0; i < sizeof(suf)/sizeof(suf[0]); i++) {
			if (s < 1024)
				break;
			s /= 1024;
		}

		snprintf(buf, sizeof(buf), "%.1f%s", s, suf[i]);
		return retstr(ret, buf);
	} else
		return WRDSE_UNDEF;
}
	
static int
exp_mimetype(char **ret, EVAL_ENV *env)
{
	if (env->ent && env->ent->type)
		return retstr(ret, env->ent->type);
	else
		return WRDSE_UNDEF;
} 

static int
exp_filetime(char **ret, EVAL_ENV *env)
{
	if (env->ent) {
		time_t t = env->ent->st.st_mtime;
		char buf[80];
		
		strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M", gmtime(&t));
		return retstr(ret, buf);
	} else
		return WRDSE_UNDEF;
}

static int
exp_filetype(char **ret, EVAL_ENV *env)
{
	char const *s = " ";
	if (env->ent)
		s = S_ISDIR(env->ent->st.st_mode) ? "DIRECTORY" : "FILE";
	return retstr(ret, s);
}

struct var_dcl {
	char const *name;
	int (*exp)(char **, EVAL_ENV *);
};

static struct var_dcl var_dcl[] = {
	{ "ROWCLASS", exp_rowclass },
	{ "FILENAME", exp_filename },
	{ "FILESIZE", exp_filesize },
	{ "FILETIME", exp_filetime },
	{ "FILETYPE", exp_filetype },
	{ "MIMETYPE", exp_mimetype },
	{ NULL }
};

static int
template_getvar(char **ret, const char *var, size_t len, void *clos)
{
	EVAL_ENV *env = clos;
	struct var_dcl *vd;

	for (vd = var_dcl; vd->name; vd++) {
		if (streq(vd->name, var, len))
			return vd->exp(ret, env);
	}
	return WRDSE_UNDEF;
}

static int
cmd_iconlookup(char **ret, char **argv, EVAL_ENV *env)
{
	ICON const *icon = NULL;
	if (argv[1]) {
		icon = icon_by_name(argv[1]);
		if (!icon && argv[2]) {
			icon = icon_by_mime(argv[2]);
			if (!icon && argv[3])
				icon = icon_by_type(argv[3]);
		}
	}
	env->icon = icon;
	return retstr(ret, icon ? icon->src : "");
}

static int
cmd_iconsrc(char **ret, char **argv, EVAL_ENV *env)
{
	char const *s = "";
	if (env->icon)
		s = env->icon->src;
	return retstr(ret, s);
}		

static int
cmd_iconalt(char **ret, char **argv, EVAL_ENV *env)
{
	char const *s = "";
	if (env->icon && env->icon->alt)
		s = env->icon->alt;
	return retstr(ret, s);
}		

static int
cmd_updir(char **ret, char **argv, EVAL_ENV *env)
{
	char *dir = argv[1];
	size_t len;
	
	if (!dir)
		dir = "/";
	len = strlen(dir);
	if (dir[len-1] == '/')
		len--;
	while (len > 0 && dir[len-1] != '/')
		len--;
	*ret = malloc(len + 1);
	if (!*ret)
		return WRDSE_NOSPACE;
	memcpy(*ret, dir, len);
	(*ret)[len] = 0;
	return WRDSE_OK;
}

static int
cmd_sortorder(char **ret, char **argv, EVAL_ENV *env)
{
	*ret = malloc(2);
	if (!*ret)
		return WRDSE_NOSPACE;
	(*ret)[0] =
		index_sort_ord_to_arg(
		    (argv[1] && index_sort_col_to_arg(env->col) == argv[1][0])
		       ? !env->ord
		       : ISO_ASC);
	(*ret)[1] = 0;
	return WRDSE_OK;
}

static int
template_command(char **ret, const char *cmd, size_t len, char **argv,
		 void *clos)
{
	if (strcmp(argv[0], "iconlookup") == 0) {
		return cmd_iconlookup(ret, argv, clos);
	}
	
	if (strcmp(argv[0], "iconsrc") == 0) {
		return cmd_iconsrc(ret, argv, clos);
	}

	if (strcmp(argv[0], "iconalt") == 0) {
		return cmd_iconalt(ret, argv, clos);
	}

	if (strcmp(argv[0], "updir") == 0) {
		return cmd_updir(ret, argv, clos);
	}

	if (strcmp(argv[0], "sortorder") == 0) {
		return cmd_sortorder(ret, argv, clos);
	}
	
	return WRDSE_UNDEF;
}

static char defidx[] =
#include "defidx.h"
	;	

int		
directory_index(int fd, CONFIG const *conf,
		char const *uri, char const *path,
	        INDEX_SORT_COL col, INDEX_SORT_ORD ord)
{
	int rc;
	DIRLS dirls;
	EVAL_ENV env;
	char const *varenv[5];

	if (index_disabled)
		return ENOSYS;
	if (STAILQ_EMPTY(&node_list)) {
		if (parse_template_string(defidx)) {
			error("error compiling built-in template!");
			index_disabled = 1;
			return ENOSYS;
		}
	}
	
	rc = dirls_scan(&dirls, path, conf);
	if (rc)
		return rc;
	dirls_sort(&dirls, col, ord);

	env.fd = fd;
	env.conf = conf;
	env.ent = STAILQ_FIRST(&dirls.list);
	env.n = 0;
	env.col = col;
	env.ord = ord;

	varenv[0] = "URI";
	varenv[1] = uri;
	varenv[2] = "INDEXCSS";
	varenv[3] = index_css;
	varenv[4] = NULL;
	
	env.ws.ws_error = error;
	env.ws.ws_getvar = template_getvar;
	env.ws.ws_command = template_command;
	env.ws.ws_closure = &env;
	env.ws.ws_env = varenv;
	env.ws.ws_options = WRDSO_ARGV;
	
	env.wsflags = WRDSF_NOSPLIT
		| WRDSF_WS
		| WRDSF_ERROR
		| WRDSF_SHOWERR 
		| WRDSF_GETVAR 
		| WRDSF_CLOSURE
		| WRDSF_OPTIONS
		| WRDSF_ENV
		| WRDSF_ENV_KV 
	        ;

	rc = node_list_eval(&node_list, &env);
	
	dirls_free(&dirls);
        if (env.wsflags & WRDSF_REUSE)
		wordsplit_free(&env.ws);
	
	return rc ? ENOSYS : 0;
}