<?php

namespace WP_CLI;

use WP_CLI;

class Completions {

    private $cur_word;
    private $words;
    private $opts = [];

    /**
     * Instantiate a Completions object.
     *
     * @param string $line Line of shell input to compute a completion for.
     */
    public function __construct( $line ) {
        // TODO: properly parse single and double quotes
        $this->words = explode( ' ', $line );

        // First word is always `wp`.
        array_shift( $this->words );

        // Last word is either empty or an incomplete subcommand.
        $this->cur_word = end( $this->words );
        if ( '' !== $this->cur_word && ! preg_match( '/^\-/', $this->cur_word ) ) {
            array_pop( $this->words );
        }

        $is_alias = false;
        $is_help  = false;
        if ( ! empty( $this->words[0] ) && preg_match( '/^@/', $this->words[0] ) ) {
            array_shift( $this->words );
            // `wp @al` is false, but `wp @all ` is true.
            if ( count( $this->words ) ) {
                $is_alias = true;
            }
        } elseif ( ! empty( $this->words[0] ) && 'help' === $this->words[0] ) {
            array_shift( $this->words );
            $is_help = true;
        }

        $r = $this->get_command( $this->words );
        if ( ! is_array( $r ) ) {
            return;
        }

        list( $command, $args, $assoc_args ) = $r;

        $spec = SynopsisParser::parse( $command->get_synopsis() );

        foreach ( $spec as $arg ) {
            if ( 'positional' === $arg['type'] && 'file' === $arg['name'] ) {
                $this->add( '<file> ' );
                return;
            }
        }

        if ( $command->can_have_subcommands() ) {
            // Add completion when command is `wp` and alias isn't set.
            if ( 'wp' === $command->get_name() && false === $is_alias && false === $is_help ) {
                $aliases = WP_CLI::get_configurator()->get_aliases();
                foreach ( $aliases as $name => $_ ) {
                    $this->add( "$name " );
                }
            }
            foreach ( $command->get_subcommands() as $name => $_ ) {
                $this->add( "$name " );
            }
        } else {
            foreach ( $spec as $arg ) {
                if ( in_array( $arg['type'], [ 'flag', 'assoc' ], true ) ) {
                    if ( isset( $assoc_args[ $arg['name'] ] ) ) {
                        continue;
                    }

                    $opt = "--{$arg['name']}";

                    if ( 'flag' === $arg['type'] ) {
                        $opt .= ' ';
                    } elseif ( ! $arg['value']['optional'] ) {
                        $opt .= '=';
                    }

                    $this->add( $opt );
                }
            }

            foreach ( $this->get_global_parameters() as $param => $runtime ) {
                if ( isset( $assoc_args[ $param ] ) ) {
                    continue;
                }

                $opt = "--{$param}";

                if ( '' === $runtime || ! is_string( $runtime ) ) {
                    $opt .= ' ';
                } else {
                    $opt .= '=';
                }

                $this->add( $opt );
            }
        }
    }

    /**
     * Get the specific WP-CLI command that is being referenced.
     *
     * @param array $words Individual input line words.
     *
     * @return array|mixed Array with command and arguments, or error result if command detection failed.
     */
    private function get_command( $words ) {
        $positional_args = [];
        $assoc_args      = [];

        # Avoid having to polyfill array_key_last().
        end( $words );
        $last_arg_i = key( $words );
        foreach ( $words as $i => $arg ) {
            if ( preg_match( '|^--([^=]+)(=?)|', $arg, $matches ) ) {
                if ( $i === $last_arg_i && '' === $matches[2] ) {
                    continue;
                }
                $assoc_args[ $matches[1] ] = true;
            } else {
                $positional_args[] = $arg;
            }
        }

        $r = WP_CLI::get_runner()->find_command_to_run( $positional_args );
        if ( ! is_array( $r ) && array_pop( $positional_args ) === $this->cur_word ) {
            $r = WP_CLI::get_runner()->find_command_to_run( $positional_args );
        }

        if ( ! is_array( $r ) ) {
            return $r;
        }

        list( $command, $args ) = $r;

        return [ $command, $args, $assoc_args ];
    }

    /**
     * Get global parameters.
     *
     * @return array Associative array of global parameters.
     */
    private function get_global_parameters() {
        $params = [];
        foreach ( WP_CLI::get_configurator()->get_spec() as $key => $details ) {
            if ( false === $details['runtime'] ) {
                continue;
            }

            if ( isset( $details['deprecated'] ) ) {
                continue;
            }

            if ( isset( $details['hidden'] ) ) {
                continue;
            }
            $params[ $key ] = $details['runtime'];

            // Add additional option like `--[no-]color`.
            if ( true === $details['runtime'] ) {
                $params[ 'no-' . $key ] = '';
            }
        }

        return $params;
    }

    /**
     * Store individual option.
     *
     * @param string $opt Option to store.
     *
     * @return void
     */
    private function add( $opt ) {
        if ( '' !== $this->cur_word ) {
            if ( 0 !== strpos( $opt, $this->cur_word ) ) {
                return;
            }
        }

        $this->opts[] = $opt;
    }

    /**
     * Render the stored options.
     *
     * @return void
     */
    public function render() {
        foreach ( $this->opts as $opt ) {
            WP_CLI::line( $opt );
        }
    }
}