// Copyright 2007-2019 David Robillard <d@drobilla.net>
// SPDX-License-Identifier: ISC

#include "filesystem.h"
#include "lilv_internal.h"

#include "lilv/lilv.h"
#include "serd/serd.h"

#include <sys/stat.h>

#include <ctype.h>
#include <errno.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void
lilv_free(void* ptr)
{
  free(ptr);
}

char*
lilv_strjoin(const char* first, ...)
{
  size_t len    = strlen(first);
  char*  result = (char*)malloc(len + 1);

  memcpy(result, first, len);

  va_list args;
  va_start(args, first);
  while (1) {
    const char* const s = va_arg(args, const char*);
    if (s == NULL) {
      break;
    }

    const size_t this_len   = strlen(s);
    char*        new_result = (char*)realloc(result, len + this_len + 1);
    if (!new_result) {
      va_end(args);
      free(result);
      return NULL;
    }

    result = new_result;
    memcpy(result + len, s, this_len);
    len += this_len;
  }
  va_end(args);

  result[len] = '\0';

  return result;
}

char*
lilv_strdup(const char* str)
{
  if (!str) {
    return NULL;
  }

  const size_t len  = strlen(str);
  char*        copy = (char*)malloc(len + 1);
  memcpy(copy, str, len + 1);
  return copy;
}

const char*
lilv_uri_to_path(const char* uri)
{
#if defined(__GNUC__) && __GNUC__ > 4
#  pragma GCC diagnostic push
#  pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif

  return (const char*)serd_uri_to_path((const uint8_t*)uri);

#if defined(__GNUC__) && __GNUC__ > 4
#  pragma GCC diagnostic pop
#endif
}

char*
lilv_file_uri_parse(const char* uri, char** hostname)
{
  return (char*)serd_file_uri_parse((const uint8_t*)uri, (uint8_t**)hostname);
}

/** Return the current LANG converted to Turtle (i.e. RFC3066) style.
 * For example, if LANG is set to "en_CA.utf-8", this returns "en-ca".
 */
char*
lilv_get_lang(void)
{
  const char* const env_lang = getenv("LANG");
  if (!env_lang || !strcmp(env_lang, "") || !strcmp(env_lang, "C") ||
      !strcmp(env_lang, "POSIX")) {
    return NULL;
  }

  const size_t env_lang_len = strlen(env_lang);
  char* const  lang         = (char*)malloc(env_lang_len + 1);
  for (size_t i = 0; i < env_lang_len + 1; ++i) {
    if (env_lang[i] == '_') {
      lang[i] = '-'; // Convert _ to -
    } else if (env_lang[i] >= 'A' && env_lang[i] <= 'Z') {
      lang[i] = env_lang[i] + ('a' - 'A'); // Convert to lowercase
    } else if (env_lang[i] >= 'a' && env_lang[i] <= 'z') {
      lang[i] = env_lang[i]; // Lowercase letter, copy verbatim
    } else if (env_lang[i] >= '0' && env_lang[i] <= '9') {
      lang[i] = env_lang[i]; // Digit, copy verbatim
    } else if (env_lang[i] == '\0' || env_lang[i] == '.') {
      // End, or start of suffix (e.g. en_CA.utf-8), finished
      lang[i] = '\0';
      break;
    } else {
      LILV_ERRORF("Illegal LANG `%s' ignored\n", env_lang);
      free(lang);
      return NULL;
    }
  }

  return lang;
}

#ifndef _WIN32

/** Append suffix to dst, update dst_len, and return the realloc'd result. */
static char*
strappend(char* dst, size_t* dst_len, const char* suffix, size_t suffix_len)
{
  dst = (char*)realloc(dst, *dst_len + suffix_len + 1);
  memcpy(dst + *dst_len, suffix, suffix_len);
  dst[(*dst_len += suffix_len)] = '\0';
  return dst;
}

/** Append the value of the environment variable var to dst. */
static char*
append_var(char* dst, size_t* dst_len, const char* var)
{
  // Get value from environment
  const char* val = getenv(var);
  if (val) { // Value found, append it
    return strappend(dst, dst_len, val, strlen(val));
  }

  // No value found, append variable reference as-is
  return strappend(strappend(dst, dst_len, "$", 1), dst_len, var, strlen(var));
}

#endif

/** Expand variables (e.g. POSIX ~ or $FOO, Windows %FOO%) in `path`. */
char*
lilv_expand(const char* path)
{
#ifdef _WIN32
  char* out = (char*)malloc(MAX_PATH);
  ExpandEnvironmentStrings(path, out, MAX_PATH);
#else
  char*  out = NULL;
  size_t len = 0;

  const char* start = path; // Start of current chunk to copy
  for (const char* s = path; *s;) {
    if (*s == '$') {
      // Hit $ (variable reference, e.g. $VAR_NAME)
      for (const char* t = s + 1;; ++t) {
        if (!*t || (!isupper(*t) && !isdigit(*t) && *t != '_')) {
          // Append preceding chunk
          out = strappend(out, &len, start, s - start);

          // Append variable value (or $VAR_NAME if not found)
          char* var = (char*)calloc(t - s, 1);
          memcpy(var, s + 1, t - s - 1);
          out = append_var(out, &len, var);
          free(var);

          // Continue after variable reference
          start = s = t;
          break;
        }
      }
    } else if (*s == '~' && (*(s + 1) == '/' || !*(s + 1))) {
      // Hit ~ before slash or end of string (home directory reference)
      out   = strappend(out, &len, start, s - start);
      out   = append_var(out, &len, "HOME");
      start = ++s;
    } else {
      ++s;
    }
  }

  if (*start) {
    out = strappend(out, &len, start, strlen(start));
  }
#endif

  return out;
}

char*
lilv_find_free_path(const char* in_path,
                    bool (*exists)(const char*, const void*),
                    const void* user_data)
{
  const size_t in_path_len = strlen(in_path);
  char*        path        = (char*)malloc(in_path_len + 7);
  memcpy(path, in_path, in_path_len + 1);

  for (unsigned i = 2; i < 1000000u; ++i) {
    if (!exists(path, user_data)) {
      return path;
    }
    snprintf(path, in_path_len + 7, "%s.%u", in_path, i);
  }

  return NULL;
}

typedef struct {
  char*  pattern;
  time_t time;
  char*  latest;
} Latest;

static void
update_latest(const char* path, const char* name, void* data)
{
  Latest*  latest     = (Latest*)data;
  char*    entry_path = lilv_path_join(path, name);
  unsigned num        = 0;
  if (sscanf(entry_path, latest->pattern, &num) == 1) {
    struct stat st;
    if (!stat(entry_path, &st)) {
      if (st.st_mtime >= latest->time) {
        free(latest->latest);
        latest->latest = entry_path;
      }
    } else {
      LILV_ERRORF("stat(%s) (%s)\n", path, strerror(errno));
    }
  }
  if (entry_path != latest->latest) {
    free(entry_path);
  }
}

/** Return the latest copy of the file at `path` that is newer. */
char*
lilv_get_latest_copy(const char* path, const char* copy_path)
{
  char*  copy_dir = lilv_path_parent(copy_path);
  Latest latest   = {lilv_strjoin(copy_path, ".%u", NULL), 0, NULL};

  struct stat st;
  if (!stat(path, &st)) {
    latest.time = st.st_mtime;
  } else {
    LILV_ERRORF("stat(%s) (%s)\n", path, strerror(errno));
  }

  lilv_dir_for_each(copy_dir, &latest, update_latest);

  free(latest.pattern);
  free(copy_dir);
  return latest.latest;
}
