<?php

namespace WP_CLI;

use WP_CLI;
use WP_CLI_Command;
use WP_CLI\Utils;

/**
 * Base class for WP-CLI commands that deal with terms
 *
 * @package wp-cli
 */
abstract class CommandWithTerms extends WP_CLI_Command {

    /**
     * @var string $object_type WordPress' expected name for the object.
     */
    protected $obj_type;

    /**
     * @var string $object_id WordPress' object id.
     */
    protected $obj_id;

    /**
     * @var array $obj_fields Default fields to display for each object.
     */
    protected $obj_fields = [
        'term_id',
        'name',
        'slug',
        'taxonomy',
    ];

    /**
     * List all terms associated with an object.
     *
     * ## OPTIONS
     *
     * <id>
     * : ID for the object.
     *
     * <taxonomy>...
     * : One or more taxonomies to list.
     *
     * [--field=<field>]
     * : Prints the value of a single field for each term.
     *
     * [--fields=<fields>]
     * : Limit the output to specific row fields.
     *
     * [--format=<format>]
     * : Render output in a particular format.
     * ---
     * default: table
     * options:
     *   - table
     *   - csv
     *   - json
     *   - yaml
     *   - count
     *   - ids
     * ---
     *
     * ## AVAILABLE FIELDS
     *
     * These fields will be displayed by default for each term:
     *
     * * term_id
     * * name
     * * slug
     * * taxonomy
     *
     * These fields are optionally available:
     *
     * * term_taxonomy_id
     * * description
     * * term_group
     * * parent
     * * count
     *
     * @subcommand list
     */
    public function list_( $args, $assoc_args ) {

        $defaults   = [
            'format' => 'table',
        ];
        $assoc_args = array_merge( $defaults, $assoc_args );

        $object_id      = array_shift( $args );
        $taxonomy_names = $args;
        $taxonomy_args  = [];

        $this->set_obj_id( $object_id );

        foreach ( $taxonomy_names as $taxonomy ) {
            $this->taxonomy_exists( $taxonomy );
        }

        if ( 'ids' === $assoc_args['format'] ) {
            $taxonomy_args['fields'] = 'ids';
        }

        $items = wp_get_object_terms( $object_id, $taxonomy_names, $taxonomy_args );

        $formatter = $this->get_formatter( $assoc_args );
        $formatter->display_items( $items );
    }


    /**
     * Remove a term from an object.
     *
     * ## OPTIONS
     *
     * <id>
     * : The ID of the object.
     *
     * <taxonomy>
     * : The name of the term's taxonomy.
     *
     * [<term>...]
     * : The slug of the term or terms to be removed from the object.
     *
     * [--by=<field>]
     * : Explicitly handle the term value as a slug or id.
     * ---
     * default: slug
     * options:
     *   - slug
     *   - id
     * ---
     *
     * [--all]
     * : Remove all terms from the object.
     */
    public function remove( $args, $assoc_args ) {
        $object_id = array_shift( $args );
        $taxonomy  = array_shift( $args );
        $terms     = $args;

        $this->set_obj_id( $object_id );

        $this->taxonomy_exists( $taxonomy );

        $field = Utils\get_flag_value( $assoc_args, 'by' );
        if ( $field ) {
            $terms = $this->prepare_terms( $field, $terms, $taxonomy );
        }

        if ( Utils\get_flag_value( $assoc_args, 'all' ) ) {

            // No need to specify terms while removing all terms.
            if ( $terms ) {
                WP_CLI::error( 'No need to specify terms while removing all terms.' );
            }

            // Remove all set categories from post.
            $result = wp_delete_object_term_relationships( $object_id, $taxonomy );

            $message = 'Removed all terms.';
            if ( 'category' === $taxonomy ) {

                // Set default category to post.
                $default_category = (int) get_option( 'default_category' );
                $default_category = ( ! empty( $default_category ) ) ? $default_category : 1;
                $default_category = wp_set_object_terms( $object_id, [ $default_category ], $taxonomy, true );

                if ( is_wp_error( $default_category ) ) {
                    WP_CLI::error( 'Failed to set default term.' );
                }

                $message = 'Removed all terms and set default term.';
            }

            if ( is_wp_error( $result ) ) {
                WP_CLI::error( 'Failed to remove all terms.' );
            }

            WP_CLI::success( $message );

            return;
        }

        // Abort if no terms are specified.
        if ( ! $terms ) {
            WP_CLI::error( 'Please specify one or more terms, or use --all.' );
        }

        // Remove term from post.
        $result = wp_remove_object_terms( $object_id, $terms, $taxonomy );

        $label = count( $terms ) > 1 ? 'terms' : 'term';

        if ( is_wp_error( $result ) ) {
            WP_CLI::error( "Failed to remove {$label}." );
        }

        WP_CLI::success( "Removed {$label}." );
    }

    /**
     * Add a term to an object.
     *
     * Append the term to the existing set of terms on the object.
     *
     * ## OPTIONS
     *
     * <id>
     * : The ID of the object.
     *
     * <taxonomy>
     * : The name of the taxonomy type to be added.
     *
     * <term>...
     * : The slug of the term or terms to be added.
     *
     * [--by=<field>]
     * : Explicitly handle the term value as a slug or id.
     * ---
     * default: slug
     * options:
     *   - slug
     *   - id
     * ---
     */
    public function add( $args, $assoc_args ) {
        $object_id = array_shift( $args );
        $taxonomy  = array_shift( $args );
        $terms     = $args;

        $this->set_obj_id( $object_id );

        $this->taxonomy_exists( $taxonomy );

        $field = Utils\get_flag_value( $assoc_args, 'by' );
        if ( $field ) {
            $terms = $this->prepare_terms( $field, $terms, $taxonomy );
        }
        $result = wp_set_object_terms( $object_id, $terms, $taxonomy, true );

        $label = count( $terms ) > 1 ? 'terms' : 'term';
        if ( ! is_wp_error( $result ) ) {
            WP_CLI::success( "Added {$label}." );
        } else {
            WP_CLI::error( "Failed to add {$label}." );
        }
    }

    /**
     * Set object terms.
     *
     * Replaces existing terms on the object.
     *
     * ## OPTIONS
     *
     * <id>
     * : The ID of the object.
     *
     * <taxonomy>
     * : The name of the taxonomy type to be updated.
     *
     * <term>...
     * : The slug of the term or terms to be updated.
     *
     * [--by=<field>]
     * : Explicitly handle the term value as a slug or id.
     * ---
     * default: slug
     * options:
     *   - slug
     *   - id
     * ---
     */
    public function set( $args, $assoc_args ) {
        $object_id = array_shift( $args );
        $taxonomy  = array_shift( $args );
        $terms     = $args;

        $this->set_obj_id( $object_id );

        $this->taxonomy_exists( $taxonomy );

        $field = Utils\get_flag_value( $assoc_args, 'by' );
        if ( $field ) {
            $terms = $this->prepare_terms( $field, $terms, $taxonomy );
        }
        $result = wp_set_object_terms( $object_id, $terms, $taxonomy, false );

        $label = count( $terms ) > 1 ? 'terms' : 'term';
        if ( ! is_wp_error( $result ) ) {
            WP_CLI::success( "Set {$label}." );
        } else {
            WP_CLI::error( "Failed to set {$label}." );
        }
    }

    /**
     * Check if taxonomy exists
     *
     * @param $taxonomy
     */
    protected function taxonomy_exists( $taxonomy ) {

        $taxonomy_names = get_object_taxonomies( $this->get_object_type() );

        if ( ! in_array( $taxonomy, $taxonomy_names, true ) ) {
            WP_CLI::error( "Invalid taxonomy {$taxonomy}." );
        }
    }

    /**
     * Prepare terms if `--by=<field>` flag is used
     *
     * @param array $terms
     * @param string $field
     * @param string $taxonomy
     */
    protected function prepare_terms( $field, $terms, $taxonomy ) {
        if ( 'id' === $field ) {
            $new_terms = [];
            foreach ( $terms as $term_id ) {
                $term = get_term_by( 'term_id', $term_id, $taxonomy );
                if ( $term ) {
                    $new_terms[] = $term->slug;
                }
            }
            $terms = $new_terms;
        }
        return $terms;
    }

    /**
     * Set obj_id Class variable
     *
     * @param string $obj_id
     */
    protected function set_obj_id( $obj_id ) {
        $this->obj_id = $obj_id;
    }

    /**
     * Get obj_id Class variable
     *
     * @return string
     */
    protected function get_obj_id() {
        return $this->obj_id;
    }


    /**
     * Get obj_type Class variable
     *
     * @return string $obj_type
     */
    protected function get_object_type() {
        return $this->obj_type;
    }

    /**
     * Get Formatter object based on supplied parameters.
     *
     * @param array $assoc_args Parameters passed to command. Determines formatting.
     *
     * @return WP_CLI\Formatter
     */
    protected function get_formatter( &$assoc_args ) {
        return new Formatter( $assoc_args, $this->obj_fields, $this->obj_type );
    }
}