module TK.SpaceTac {
    /**
     * Category of action
     */
    export enum ActionCategory {
        MOVE,
        PASSIVE,
        ACTIVE,
    }

    /**
     * Target for an action
     */
    export type ActionTarget = Readonly<{
        distance?: number
        angle?: number
    }>

    /**
     * Target for an action, as applied from an hypothetical location
     */
    export type ActionTargetFrom = Readonly<{
        location: IArenaLocation
        distance?: number
        angle?: number
    }>

    /**
     * Impact filter for an action.
     * 
     * This will filter ships inside the targetted area, to determine which ones will receive the action effects.
     */
    export enum ActionImpactFilter {
        // Apply only on casting ship
        SELF,
        // Apply on all ships
        ALL,
        // Apply on all ships except the actor
        ALL_BUT_SELF,
        // Apply on all allies, including the actor
        ALLIES,
        // Apply on all allies, except the actor
        ALLIES_BUT_SELF,
        // Apply on all enemies
        ENEMIES,
    };

    /**
     * Priority of ships in the target area.
     * 
     * If there are more ships that the action limit, the most prioritized ones will be affected.
     */
    export enum ActionImpactPriority {
        // Nearest ships are priority
        NEAREST,
        // Farthest ships are priority
        FARTHEST,
        // Ships with the most hull are priority
        TOUGHEST,
        // Ships with the less hull are priority
        WEAKEST,
    }

    /**
     * Configuration for the target of an action
     */
    export interface BaseActionConfig {
        // Identifying code (for assets and effects)
        code: string
        // Human-friendly name
        name: string
        // Power cost
        power_cost?: number
        // Maximal distance the target can be set
        min_distance?: number
        // Minimal distance the target can be set
        max_distance?: number
        // Angle that will span the affected area (around the target direction)
        angular_span?: number
        // Radius of the affected area (around the target location)
        radius?: number
        // Filtering of ships in the affected area
        ship_filter?: ActionImpactFilter
        // Maximal number of ships impacted in the affected area
        ship_limit?: number
        // Priority of ships in affected area
        ship_priority?: ActionImpactPriority
    }

    /**
     * Reasons for action unavailibility
     */
    export enum ActionUnavailability {
        // Ship is not playing
        NOT_PLAYING = "Not this ship turn",
        // Action is not available
        NO_SUCH_ACTION = "Action not available",
        // Action is overheated
        OVERHEATED = "Overheated",
        // Vigilance is activated
        VIGILANCE = "In vigilance",
        // Ship is pinned
        PINNED = "Pinned",
    }

    /**
     * Base class for a battle action.
     * 
     * An action should be the only way to modify a battle state.
     */
    export class BaseAction extends RObject implements BaseActionConfig {
        code = "nothing"
        name = "Nothing"
        power_cost = 0
        min_distance = 0
        max_distance = Infinity
        angular_span = undefined
        radius = undefined
        ship_filter = ActionImpactFilter.ALL
        ship_limit = undefined
        ship_priority = ActionImpactPriority.NEAREST

        // Cooldown configuration
        private cooldown = new Cooldown()

        // Create the action
        constructor(config?: Partial<Readonly<BaseActionConfig>>) {
            super();

            if (config) {
                this.configure(config);
            }
        }

        /**
         * Get the category for this action
         */
        getCategory(): ActionCategory {
            return ActionCategory.PASSIVE;
        }

        /**
         * Get the verb for this action
         */
        getVerb(ship: Ship): string {
            return "Do";
        }

        /**
         * Get the full title for this action (verb and name)
         */
        getTitle(ship: Ship): string {
            return `${this.getVerb(ship)} ${this.name}`;
        }

        /**
         * Get a default target for this action
         */
        getDefaultTarget(ship: Ship): ActionTargetFrom {
            return { location: ship.location };
        }

        /**
         * Configure the base settings for this action
         */
        configure(config: Partial<Readonly<BaseActionConfig>>): void {
            copyfields(config, this);
        }

        /**
         * Configure the cooldown for this action
         */
        configureCooldown(overheat: number, cooling: number): void {
            this.cooldown.configure(overheat, cooling);
        }

        /**
         * Get the cooldown configuration
         */
        getCooldown(): Cooldown {
            // TODO Split configuration (readonly) and usage
            return this.cooldown;
        }

        /**
         * Check basic conditions to know if the ship can use this action at all, not accounting for power
         * 
         * Method to extend to set conditions
         * 
         * Returns an unavalability reason, null otherwise
         */
        checkCannotBeApplied(ship: Ship): ActionUnavailability | null {
            if (!ship.actions.getById(this.id)) {
                return ActionUnavailability.NO_SUCH_ACTION;
            }

            // Check cooldown
            if (!ship.actions.isUsable(this)) {
                return ActionUnavailability.OVERHEATED;
            }

            return null;
        }

        /**
         * Get the power cost of this action for the current state
         */
        getPowerUsage(ship: Ship): number {
            return this.power_cost;
        }

        /**
         * Filter a list of ships to return only those impacted by this action
         * 
         * This may be used as an indicator for helping the player in targetting, or to effectively apply the effects
         */
        filterImpactedShips(ships: readonly Ship[], source: Ship, target: ActionTargetFrom): readonly Ship[] {
            // TODO Allow to work with ghosts (location instead of ships?)
            // TODO Apply radius and angle
            // TODO Apply limit and priority
            return ships.filter(ship => {
                if (this.ship_filter == ActionImpactFilter.ALL) {
                    return true;
                } else if (this.ship_filter == ActionImpactFilter.ALL_BUT_SELF) {
                    return !ship.is(source);
                } else if (this.ship_filter == ActionImpactFilter.ALLIES) {
                    return ship.fleet.player.is(source.fleet.player);
                } else if (this.ship_filter == ActionImpactFilter.ALLIES_BUT_SELF) {
                    return ship.fleet.player.is(source.fleet.player) && !ship.is(source);
                } else if (this.ship_filter == ActionImpactFilter.ENEMIES) {
                    return !ship.fleet.player.is(source.fleet.player);
                } else {
                    return false;
                }
            });
        }

        /**
         * Get a name to represent the group of ships specified by a target filter
         */
        static getFilterDesc(filter: ActionImpactFilter, plural = true): string {
            // TODO limit and priority
            if (filter == ActionImpactFilter.ALL) {
                return plural ? "ships" : "ship";
            } else if (filter == ActionImpactFilter.ALL_BUT_SELF) {
                return plural ? "other ships" : "other ship";
            } else if (filter == ActionImpactFilter.ALLIES) {
                return plural ? "team members" : "team member";
            } else if (filter == ActionImpactFilter.ALLIES_BUT_SELF) {
                return plural ? "teammates" : "teammates";
            } else if (filter == ActionImpactFilter.ENEMIES) {
                return plural ? "enemies" : "enemy";
            } else {
                return "";
            }
        }

        /**
         * Check if a target is suitable for this action
         * 
         * Returns a suggested fixed target (may be the same as the input)
         */
        checkTarget(ship: Ship, target: ActionTargetFrom): ActionTargetFrom | null {
            if (this.checkCannotBeApplied(ship)) {
                return null;
            } else {
                if (target.isShip()) {
                    return this.checkShipTarget(ship, target);
                } else {
                    return this.checkLocationTarget(ship, target);
                }
            }
        }

        /**
         * Get the full list of diffs caused by applying this action
         * 
         * This does not perform any check, and assumes the action is doable
         */
        getDiffs(ship: Ship, battle: Battle, target: ActionTargetFrom): BaseBattleDiff[] {
            let result: BaseBattleDiff[] = [];

            // Action usage
            result.push(new ShipActionUsedDiff(ship, this, target));

            // Action effects
            result = result.concat(this.getSpecificDiffs(ship, battle, target));

            return result;
        }

        /**
         * Method to reimplement to return the diffs specific to this action
         */
        protected getSpecificDiffs(ship: Ship, battle: Battle, target: ActionTargetFrom): BaseBattleDiff[] {
            return []
        }

        /**
         * Apply the action on a battle state
         * 
         * This will first check that the action can be done, then get the battle diffs and apply them.
         */
        apply(battle: Battle, ship: Ship, target: ActionTarget): boolean {
            let reject = this.checkCannotBeApplied(ship);
            if (reject) {
                console.warn(`Action rejected - ${reject}`, ship, this, target);
                return false;
            }

            let checked_target = this.checkTarget(ship, target);
            if (!checked_target) {
                console.warn("Action rejected - invalid target", ship, this, target);
                return false;
            }

            let diffs = this.getDiffs(ship, battle, checked_target);
            if (diffs.length) {
                battle.applyDiffs(diffs);
                return true;
            } else {
                console.error("Could not apply action, no diff produced");
                return false;
            }
        }

        /**
         * Get textual description of effects
         */
        getEffectsDescription(): string {
            return "";
        }
    }
}