import is from '@sindresorhus/is';
import moo from 'moo';
import { logger } from '../../../logger';
import type {
  EdnMetadata,
  ParsedEdnArray,
  ParsedEdnMetadata,
  ParsedEdnRecord,
  ParsedEdnResult,
  ParserState,
  TokenTypes,
} from './types';

const lexerStates = {
  main: {
    comma: { match: ',' },
    lineComment: { match: /;.*?$/ },
    leftParen: { match: '(' },
    rightParen: { match: ')' },
    leftSquare: { match: '[' },
    rightSquare: { match: ']' },
    leftFigure: { match: '{' },
    rightFigure: { match: '}' },
    longDoubleQuoted: {
      match: '"""',
      push: 'longDoubleQuoted',
    },
    doubleQuoted: {
      match: '"',
      push: 'doubleQuoted',
    },
    // https://clojure.org/reference/reader#_reader_forms
    keyword: {
      match:
        /:(?:[a-zA-Z*+!_'?<>=.-][a-zA-Z0-9*+!_'?<>=.-]*)(?:\/(?:[a-zA-Z*+!_'?<>=.-][a-zA-Z0-9*+!_'?<>=.-]*))?/,
      value: (x: string) => x.slice(1),
    },
    symbol: {
      match:
        /(?:[a-zA-Z*+!_'?<>=.-][a-zA-Z0-9*+!_'?<>=.-]*)(?:\/(?:[a-zA-Z*+!_'?<>=.-][a-zA-Z0-9*+!_'?<>=.-]*))?/,
    },
    double: {
      match:
        /(?:[0-9]+\.[0-9]*|[0-9]*\.[0-9]+)(?:[eE][+-]?[0-9]+)?|(?:[0-9]+[eE][+-]?[0-9]+)/,
    },
    rational: { match: /[0-9]+\/[0-9]+/ },
    integer: { match: /(?:0x[0-9a-fA-F]+|[0-9]+r[0-9a-zA-Z]+|[0-9]+)/ },
    unknown: moo.fallback,
  },
  longDoubleQuoted: {
    stringFinish: { match: '"""', pop: 1 },
    stringContent: moo.fallback,
  },
  doubleQuoted: {
    stringFinish: { match: '"', pop: 1 },
    stringContent: moo.fallback,
  },
};

type TokenType = TokenTypes<typeof lexerStates>;

const lexer = moo.states(lexerStates);

export function parseDepsEdnFile(content: string): ParsedEdnResult | null {
  lexer.reset(content);
  const tokens = [...lexer];
  lexer.reset();

  const stack: ParserState[] = [];
  let state: ParserState = { type: 'root', data: null };

  const metadata: ParsedEdnMetadata = new WeakMap<
    ParsedEdnRecord | ParsedEdnArray,
    EdnMetadata
  >();

  const popState = (): boolean => {
    const savedState = stack.pop();
    if (!savedState) {
      return false;
    }

    if (savedState.type === 'root') {
      savedState.data = state.data;
      state = savedState;
      return false;
    }

    if (savedState.type === 'record') {
      if (savedState.skipKey) {
        savedState.currentKey = null;
        savedState.skipKey = false;
      } else if (savedState.currentKey) {
        savedState.data[savedState.currentKey] = state.data;
        savedState.currentKey = null;
      } else {
        savedState.skipKey = true;
      }
    }

    if (savedState.type === 'array') {
      savedState.data.push(state.data);
    }

    state = savedState;
    return true;
  };

  for (const token of tokens) {
    const tokenType = token.type as TokenType;
    const stateType = state.type;

    // istanbul ignore else: token type comprehension
    if (
      tokenType === 'lineComment' ||
      tokenType === 'unknown' ||
      tokenType === 'doubleQuoted' ||
      tokenType === 'longDoubleQuoted' ||
      tokenType === 'stringFinish' ||
      tokenType === 'comma'
    ) {
      continue;
    } else if (
      tokenType === 'rightParen' ||
      tokenType === 'rightSquare' ||
      tokenType === 'rightFigure'
    ) {
      if (state.type === 'record' || state.type === 'array') {
        const { startIndex } = state;
        const endIndex = token.offset + token.value.length;
        const replaceString = content.slice(startIndex, endIndex);
        metadata.set(state.data, { replaceString });
      }

      if (!popState()) {
        break;
      }
    } else if (tokenType === 'leftParen' || tokenType === 'leftSquare') {
      stack.push(state);
      state = {
        type: 'array',
        startIndex: token.offset,
        data: [],
      };
    } else if (tokenType === 'leftFigure') {
      stack.push(state);
      state = {
        type: 'record',
        startIndex: token.offset,
        data: {},
        skipKey: false,
        currentKey: null,
      };
    } else if (
      tokenType === 'symbol' ||
      tokenType === 'keyword' ||
      tokenType === 'stringContent' ||
      tokenType === 'double' ||
      tokenType === 'rational' ||
      tokenType === 'integer'
    ) {
      if (stateType === 'record') {
        if (state.skipKey) {
          state.currentKey = null;
          state.skipKey = false;
        } else if (state.currentKey) {
          state.data[state.currentKey] = token.value;
          state.currentKey = null;
        } else {
          state.currentKey = token.value;
        }
      } else if (stateType === 'array') {
        state.data.push(token.value);
      } else if (stateType === 'root') {
        state.data = token.value;
      }
    } else {
      const unknownType: never = tokenType;
      logger.debug({ unknownType }, `Unknown token type for "deps.edn"`);
    }
  }

  while (stack.length) {
    popState();
  }

  if (is.plainObject(state.data)) {
    return { data: state.data, metadata };
  }

  return null;
}