// Copyright the Browserify authors. MIT License.
// Ported from https://github.com/browserify/path-browserify/

const { cwd } = Deno;
import { FormatInputPathObject, ParsedPath } from "./interface.ts";
import { CHAR_DOT, CHAR_FORWARD_SLASH } from "./constants.ts";

import {
  assertPath,
  normalizeString,
  isPosixPathSeparator,
  _format
} from "./utils.ts";

export const sep = "/";
export const delimiter = ":";

// path.resolve([from ...], to)
export function resolve(...pathSegments: string[]): string {
  let resolvedPath = "";
  let resolvedAbsolute = false;

  for (let i = pathSegments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
    let path: string;

    if (i >= 0) path = pathSegments[i];
    else path = cwd();

    assertPath(path);

    // Skip empty entries
    if (path.length === 0) {
      continue;
    }

    resolvedPath = `${path}/${resolvedPath}`;
    resolvedAbsolute = path.charCodeAt(0) === CHAR_FORWARD_SLASH;
  }

  // At this point the path should be resolved to a full absolute path, but
  // handle relative paths to be safe (might happen when process.cwd() fails)

  // Normalize the path
  resolvedPath = normalizeString(
    resolvedPath,
    !resolvedAbsolute,
    "/",
    isPosixPathSeparator
  );

  if (resolvedAbsolute) {
    if (resolvedPath.length > 0) return `/${resolvedPath}`;
    else return "/";
  } else if (resolvedPath.length > 0) return resolvedPath;
  else return ".";
}

export function normalize(path: string): string {
  assertPath(path);

  if (path.length === 0) return ".";

  const isAbsolute = path.charCodeAt(0) === CHAR_FORWARD_SLASH;
  const trailingSeparator =
    path.charCodeAt(path.length - 1) === CHAR_FORWARD_SLASH;

  // Normalize the path
  path = normalizeString(path, !isAbsolute, "/", isPosixPathSeparator);

  if (path.length === 0 && !isAbsolute) path = ".";
  if (path.length > 0 && trailingSeparator) path += "/";

  if (isAbsolute) return `/${path}`;
  return path;
}

export function isAbsolute(path: string): boolean {
  assertPath(path);
  return path.length > 0 && path.charCodeAt(0) === CHAR_FORWARD_SLASH;
}

export function join(...paths: string[]): string {
  if (paths.length === 0) return ".";
  let joined: string | undefined;
  for (let i = 0, len = paths.length; i < len; ++i) {
    let path = paths[i];
    assertPath(path);
    if (path.length > 0) {
      if (!joined) joined = path;
      else joined += `/${path}`;
    }
  }
  if (!joined) return ".";
  return normalize(joined);
}

export function relative(from: string, to: string): string {
  assertPath(from);
  assertPath(to);

  if (from === to) return "";

  from = resolve(from);
  to = resolve(to);

  if (from === to) return "";

  // Trim any leading backslashes
  let fromStart = 1;
  let fromEnd = from.length;
  for (; fromStart < fromEnd; ++fromStart) {
    if (from.charCodeAt(fromStart) !== CHAR_FORWARD_SLASH) break;
  }
  let fromLen = fromEnd - fromStart;

  // Trim any leading backslashes
  let toStart = 1;
  const toEnd = to.length;
  for (; toStart < toEnd; ++toStart) {
    if (to.charCodeAt(toStart) !== CHAR_FORWARD_SLASH) break;
  }
  let toLen = toEnd - toStart;

  // Compare paths to find the longest common path from root
  let length = fromLen < toLen ? fromLen : toLen;
  let lastCommonSep = -1;
  let i = 0;
  for (; i <= length; ++i) {
    if (i === length) {
      if (toLen > length) {
        if (to.charCodeAt(toStart + i) === CHAR_FORWARD_SLASH) {
          // We get here if `from` is the exact base path for `to`.
          // For example: from='/foo/bar'; to='/foo/bar/baz'
          return to.slice(toStart + i + 1);
        } else if (i === 0) {
          // We get here if `from` is the root
          // For example: from='/'; to='/foo'
          return to.slice(toStart + i);
        }
      } else if (fromLen > length) {
        if (from.charCodeAt(fromStart + i) === CHAR_FORWARD_SLASH) {
          // We get here if `to` is the exact base path for `from`.
          // For example: from='/foo/bar/baz'; to='/foo/bar'
          lastCommonSep = i;
        } else if (i === 0) {
          // We get here if `to` is the root.
          // For example: from='/foo'; to='/'
          lastCommonSep = 0;
        }
      }
      break;
    }
    let fromCode = from.charCodeAt(fromStart + i);
    let toCode = to.charCodeAt(toStart + i);
    if (fromCode !== toCode) break;
    else if (fromCode === CHAR_FORWARD_SLASH) lastCommonSep = i;
  }

  let out = "";
  // Generate the relative path based on the path difference between `to`
  // and `from`
  for (i = fromStart + lastCommonSep + 1; i <= fromEnd; ++i) {
    if (i === fromEnd || from.charCodeAt(i) === CHAR_FORWARD_SLASH) {
      if (out.length === 0) out += "..";
      else out += "/..";
    }
  }

  // Lastly, append the rest of the destination (`to`) path that comes after
  // the common path parts
  if (out.length > 0) return out + to.slice(toStart + lastCommonSep);
  else {
    toStart += lastCommonSep;
    if (to.charCodeAt(toStart) === CHAR_FORWARD_SLASH) ++toStart;
    return to.slice(toStart);
  }
}

export function toNamespacedPath(path: string): string {
  // Non-op on posix systems
  return path;
}

export function dirname(path: string): string {
  assertPath(path);
  if (path.length === 0) return ".";
  const hasRoot = path.charCodeAt(0) === CHAR_FORWARD_SLASH;
  let end = -1;
  let matchedSlash = true;
  for (let i = path.length - 1; i >= 1; --i) {
    if (path.charCodeAt(i) === CHAR_FORWARD_SLASH) {
      if (!matchedSlash) {
        end = i;
        break;
      }
    } else {
      // We saw the first non-path separator
      matchedSlash = false;
    }
  }

  if (end === -1) return hasRoot ? "/" : ".";
  if (hasRoot && end === 1) return "//";
  return path.slice(0, end);
}

export function basename(path: string, ext = ""): string {
  if (ext !== undefined && typeof ext !== "string")
    throw new TypeError('"ext" argument must be a string');
  assertPath(path);

  let start = 0;
  let end = -1;
  let matchedSlash = true;
  let i: number;

  if (ext !== undefined && ext.length > 0 && ext.length <= path.length) {
    if (ext.length === path.length && ext === path) return "";
    let extIdx = ext.length - 1;
    let firstNonSlashEnd = -1;
    for (i = path.length - 1; i >= 0; --i) {
      const code = path.charCodeAt(i);
      if (code === CHAR_FORWARD_SLASH) {
        // If we reached a path separator that was not part of a set of path
        // separators at the end of the string, stop now
        if (!matchedSlash) {
          start = i + 1;
          break;
        }
      } else {
        if (firstNonSlashEnd === -1) {
          // We saw the first non-path separator, remember this index in case
          // we need it if the extension ends up not matching
          matchedSlash = false;
          firstNonSlashEnd = i + 1;
        }
        if (extIdx >= 0) {
          // Try to match the explicit extension
          if (code === ext.charCodeAt(extIdx)) {
            if (--extIdx === -1) {
              // We matched the extension, so mark this as the end of our path
              // component
              end = i;
            }
          } else {
            // Extension does not match, so our result is the entire path
            // component
            extIdx = -1;
            end = firstNonSlashEnd;
          }
        }
      }
    }

    if (start === end) end = firstNonSlashEnd;
    else if (end === -1) end = path.length;
    return path.slice(start, end);
  } else {
    for (i = path.length - 1; i >= 0; --i) {
      if (path.charCodeAt(i) === CHAR_FORWARD_SLASH) {
        // If we reached a path separator that was not part of a set of path
        // separators at the end of the string, stop now
        if (!matchedSlash) {
          start = i + 1;
          break;
        }
      } else if (end === -1) {
        // We saw the first non-path separator, mark this as the end of our
        // path component
        matchedSlash = false;
        end = i + 1;
      }
    }

    if (end === -1) return "";
    return path.slice(start, end);
  }
}

export function extname(path: string): string {
  assertPath(path);
  let startDot = -1;
  let startPart = 0;
  let end = -1;
  let matchedSlash = true;
  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  let preDotState = 0;
  for (let i = path.length - 1; i >= 0; --i) {
    const code = path.charCodeAt(i);
    if (code === CHAR_FORWARD_SLASH) {
      // If we reached a path separator that was not part of a set of path
      // separators at the end of the string, stop now
      if (!matchedSlash) {
        startPart = i + 1;
        break;
      }
      continue;
    }
    if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // extension
      matchedSlash = false;
      end = i + 1;
    }
    if (code === CHAR_DOT) {
      // If this is our first dot, mark it as the start of our extension
      if (startDot === -1) startDot = i;
      else if (preDotState !== 1) preDotState = 1;
    } else if (startDot !== -1) {
      // We saw a non-dot and non-path separator before our dot, so we should
      // have a good chance at having a non-empty extension
      preDotState = -1;
    }
  }

  if (
    startDot === -1 ||
    end === -1 ||
    // We saw a non-dot character immediately before the dot
    preDotState === 0 ||
    // The (right-most) trimmed path component is exactly '..'
    (preDotState === 1 && startDot === end - 1 && startDot === startPart + 1)
  ) {
    return "";
  }
  return path.slice(startDot, end);
}

export function format(pathObject: FormatInputPathObject): string {
  if (pathObject === null || typeof pathObject !== "object") {
    throw new TypeError(
      `The "pathObject" argument must be of type Object. Received type ${typeof pathObject}`
    );
  }
  return _format("/", pathObject);
}

export function parse(path: string): ParsedPath {
  assertPath(path);

  let ret: ParsedPath = { root: "", dir: "", base: "", ext: "", name: "" };
  if (path.length === 0) return ret;
  let isAbsolute = path.charCodeAt(0) === CHAR_FORWARD_SLASH;
  let start: number;
  if (isAbsolute) {
    ret.root = "/";
    start = 1;
  } else {
    start = 0;
  }
  let startDot = -1;
  let startPart = 0;
  let end = -1;
  let matchedSlash = true;
  let i = path.length - 1;

  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  let preDotState = 0;

  // Get non-dir info
  for (; i >= start; --i) {
    const code = path.charCodeAt(i);
    if (code === CHAR_FORWARD_SLASH) {
      // If we reached a path separator that was not part of a set of path
      // separators at the end of the string, stop now
      if (!matchedSlash) {
        startPart = i + 1;
        break;
      }
      continue;
    }
    if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // extension
      matchedSlash = false;
      end = i + 1;
    }
    if (code === CHAR_DOT) {
      // If this is our first dot, mark it as the start of our extension
      if (startDot === -1) startDot = i;
      else if (preDotState !== 1) preDotState = 1;
    } else if (startDot !== -1) {
      // We saw a non-dot and non-path separator before our dot, so we should
      // have a good chance at having a non-empty extension
      preDotState = -1;
    }
  }

  if (
    startDot === -1 ||
    end === -1 ||
    // We saw a non-dot character immediately before the dot
    preDotState === 0 ||
    // The (right-most) trimmed path component is exactly '..'
    (preDotState === 1 && startDot === end - 1 && startDot === startPart + 1)
  ) {
    if (end !== -1) {
      if (startPart === 0 && isAbsolute) {
        ret.base = ret.name = path.slice(1, end);
      } else {
        ret.base = ret.name = path.slice(startPart, end);
      }
    }
  } else {
    if (startPart === 0 && isAbsolute) {
      ret.name = path.slice(1, startDot);
      ret.base = path.slice(1, end);
    } else {
      ret.name = path.slice(startPart, startDot);
      ret.base = path.slice(startPart, end);
    }
    ret.ext = path.slice(startDot, end);
  }

  if (startPart > 0) ret.dir = path.slice(0, startPart - 1);
  else if (isAbsolute) ret.dir = "/";

  return ret;
}