import SimpleSchema from 'simpl-schema';
import { forEach, isEmpty, pick } from 'lodash';
import LogContentSchema from '/imports/api/creature/log/LogContentSchema';
import { getPropertyChildren, getSingleProperty, getVariables } from '/imports/api/engine/loadCreatures';
import recalculateInlineCalculations from '/imports/api/engine/actions/applyPropertyByType/shared/recalculateInlineCalculations';
import recalculateCalculation from '/imports/api/engine/actions/applyPropertyByType/shared/recalculateCalculation';
import rollDice from '/imports/parser/rollDice';

const Actions = new Mongo.Collection<ActionWithId>('actions');

export interface Action {
  creatureId: string;
  rootPropId: string;
  targetIds?: string[];
  userInputNeeded?: any;
  stepThrough?: boolean;
  taskQueue: Task[];
  taskProperties: any;
  deferredResults: { [id: string]: PartialTaskResult };
  results: TaskResult[];
}

interface ActionWithId extends Action {
  _id: string;
}

type Task = {
  propId: string;
  targetIds: string[];
  step?: number,
}

type TaskResult = {
  propId: string;
  targetIds: string[];
  scope: any;
  mutations: Mutation[];
}

class PartialTaskResult {
  scope: any;
  mutations: Mutation[];
  constructor() {
    this.scope = {};
    this.mutations = [];
  }
  // Appends the log content to the latest mutation
  appendLog(content: LogContent, targetIds: string[]) {
    if (!this.mutations.length) {
      this.mutations.push({ targetIds, contents: [] });
    }
    const latestMutation = this.mutations[this.mutations.length - 1]
    if (!latestMutation.contents) {
      latestMutation.contents = [];
    }
    latestMutation.contents.push(content);
  }
}

type Mutation = {
  // Which creatures the mutation is applied to
  targetIds: string[];
  // What changes in the database
  updates?: Update[];
  // Logged when this is applied
  contents?: LogContent[];
}

export type Update = {
  propId: string;
  type: string,
  set?: any;
  inc?: any;
}

export type LogContent = {
  name?: string;
  value?: string;
  inline?: boolean;
  context?: any;
  silenced?: boolean;
}

const ActionSchema = new SimpleSchema({
  creatureId: {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  rootPropId: {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  targetIds: {
    type: Array,
    defaultValue: [],
  },
  'targetIds.$': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  userInputNeeded: {
    type: Object,
    optional: true,
    blackbox: true,
  },
  stepThrough: {
    type: Boolean,
    defaultValue: false,
  },

  // A stack of tasks to apply
  // Each task has a propId to apply and a targetId list
  taskQueue: {
    type: Array,
  },
  'taskQueue.$': {
    type: Object,
  },
  'taskQueue.$.propId': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  'taskQueue.$.step': {
    type: Number,
    optional: true,
  },
  'taskQueue.$.targetIds': {
    type: Array,
    defaultValue: [],
  },
  'taskQueue.$.targetIds.$': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },

  // Pseudo properties that don't exist on the character, but can be applied by the action
  // {_id: prop}
  'taskProperties': {
    type: Object,
    blackbox: true,
    defaultValue: {},
  },
  // Results that have been partially computed, but require more steps
  // {_id: partialResult}
  'deferredResults': {
    type: Object,
    blackbox: true,
    defaultValue: {},
  },

  // Applied properties
  results: {
    type: Array,
    defaultValue: [],
  },
  'results.$': {
    type: Object,
  },
  // The property and target ids popped off the task stack
  // Pushing these to the top of the stack and deleting the results from this point onwards
  // Should re-run the action identically from this point
  'results.$.propId': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  'results.$.targetIds': {
    type: Array,
    defaultValue: [],
  },
  'results.$.targetIds.$': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  // Changes in local scope made by this result
  'results.$.scope': {
    type: Object,
    optional: true,
    blackbox: true,
  },
  // database changes
  'results.$.mutations': {
    type: Array,
    optional: true,
  },
  'results.$.mutations.$': {
    type: Object,
  },
  'results.$.mutations.$.targetIds': {
    type: Array,
  },
  'results.$.mutations.$.targetIds.$': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  'results.$.mutations.$.updates': {
    type: Array,
    optional: true,
  },
  'results.$.mutations.$.updates.$': {
    type: Object,
  },
  'results.$.mutations.$.updates.$.propId': {
    type: String,
    regEx: SimpleSchema.RegEx.Id,
  },
  // Required, because CreatureProperties.update requires a selector of { type }
  'results.$.mutations.$.updates.$.type': {
    type: String,
  },
  'results.$.mutations.$.updates.$.set': {
    type: Object,
    optional: true,
    blackbox: true,
  },
  'results.$.mutations.$.updates.$.inc': {
    type: Object,
    optional: true,
    blackbox: true,
  },
  'results.$.mutations.$.contents': {
    type: Array,
    optional: true,
  },
  'results.$.mutations.$.contents.$': {
    type: LogContentSchema,
  },
});

// @ts-expect-error Collections2 lacks TypeScript support
Actions.attachSchema(ActionSchema);

export default Actions;

/**
 * Create a new action ready to be run starting at the given property (or its 'before' triggers)
 * @param prop 
 */
export function createAction(prop) {
  const action: Action = {
    creatureId: prop.ancestors[0].id,
    rootPropId: prop._id,
    taskQueue: [],
    taskProperties: {},
    deferredResults: {},
    results: [],
  };
  pushPropAndTriggers(action, prop);
  return Actions.insertAsync(action);
}

// Run an already created action
export async function runAction(actionId: string, userInput?) {
  const action = await Actions.findOneAsync(actionId);
  if (!action) throw new Meteor.Error('Not found', 'The action does not exist');
  const originalAction = EJSON.clone(action);
  let count = 0;
  do {
    // If there isn't a next task, stop
    if (!action.taskQueue.length) break;
    await applyNextTask(action, userInput);
    count += 1;
    if (count > 100) {
      break;
    }
  } while (!action.userInputNeeded && !action.stepThrough)

  // Persist changes to the action
  const writePromise = writeChangedAction(originalAction, action);
  if (count > 100) {
    throw new Meteor.Error('Too many properties', 'Only 100 properties may fire at a time');
  }
  return writePromise;
}

// TODO create a function to get the effective value of a property,
// simulating all the result updates in the action so far

async function applyNextTask(action: Action, userInput?) {
  // Get the next task
  const task = action.taskQueue.shift();
  if (!task) throw 'Next task does not exist';
  // Get the property from the action's task properties or the creature's properties
  let prop;
  const taskProp = action.taskProperties[task.propId];
  if (taskProp) {
    prop = taskProp;
  } else {
    prop = await getSingleProperty(action.creatureId, task.propId);
  }
  // Ensure the prop exists
  if (!prop) throw new Meteor.Error('Not found', 'Property could not be found');
  if (prop.deactivatedByToggle) return;

  // Apply the property
  const result: PartialTaskResult = await applyPropertyByType[prop.type]?.(prop, task, action, userInput);
  // store the task's details and save the result
  result.scope[`#${prop.type}`] = prop;
  action.results.push({
    propId: task.propId,
    targetIds: task.targetIds,
    scope: result.scope,
    mutations: result.mutations,
  });
}

function writeChangedAction(original: ActionWithId, changed: ActionWithId) {
  const $set = {};
  for (const key of ActionSchema.objectKeys()) {
    if (!EJSON.equals(original[key], changed[key])) {
      $set[key] = changed[key];
    }
  }
  if (!isEmpty($set)) {
    return Actions.updateAsync(original._id, { $set });
  }
}

/**
 * Push a prop and its before/after triggers to the task stack
 * Triggers will share the same targetIds as the prop task
 * @param action The action to add the task to
 * @param prop The property to make a task of
 * @param targetIds The targetIds the prop and triggers will apply to
 */
function pushPropAndTriggers(action: Action, prop, targetIds?) {
  // Push the before triggers to the queue
  forEach(prop.triggerIds?.before, triggerId => {
    action.taskQueue.push({ propId: triggerId, targetIds });
  });

  // Push the prop task to the queue
  action.taskQueue.push({ propId: prop._id, targetIds });

  // Push the after triggers to the queue
  forEach(prop.triggerIds?.after, triggerId => {
    action.taskQueue.push({ propId: triggerId, targetIds });
  });
}

/**
 * Push all the children of a prop and all trigger of those children to the task queue
 * @param action The action to add the task to
 * @param prop The property to make a task of
 * @param targetIds The targetIds the prop and triggers will apply to
 */
async function pushChildren(action: Action, prop, targetIds) {
  const children = await getPropertyChildren(action.creatureId, prop._id);
  // Push the child tasks and related triggers to the stack
  forEach(children, childProp => {
    pushPropAndTriggers(action, childProp, targetIds);
  });
}

function pushAfterChildrenTriggers(action: Action, prop, targetIds) {
  forEach(prop.triggerIds?.afterChildren, triggerId => {
    action.taskQueue.push({ propId: triggerId, targetIds });
  });
}

function createResult(): PartialTaskResult {
  // Add  the property to the action's local scope
  return new PartialTaskResult();
}

// Combine all the action results into the scope at present
export function getEffectiveActionScope(action: Action) {
  const scope = getVariables(action.creatureId);
  // First combine the applied results
  for (const result of action.results) {
    Object.assign(scope, result.scope);
  }
  // Then the deferred results
  // Warning: order is not guaranteed here
  for (const id in action.deferredResults) {
    const result = action.deferredResults[id];
    Object.assign(scope, result.scope);
  }
  return scope;
}

type DamageProp = {
  _id?: string;
  operation: 'increment' | 'set';
  type: 'damageProp';
  value: number;
  targetPropId: string;
}

function pushDamagePropertyTasks(action, damageProp: DamageProp, targetProp, targetIds, result: PartialTaskResult) {
  // Save the values to the scope
  if (damageProp.operation === 'increment') {
    if (damageProp.value >= 0) {
      result.scope['~damage'] = { value: damageProp.value };
    } else {
      result.scope['~healing'] = { value: -damageProp.value };
    }
  } else {
    result.scope['~set'] = { value: damageProp.value };
  }
  // Push before triggers
  if (targetProp.triggers?.damageProperty?.before) {
    for (const triggerId of targetProp.triggers.damageProperty.before) {
      action.taskQueue.push({ propId: triggerId, targetIds });
    }
  }

  // Push damage pseudo prop
  if (!damageProp._id) damageProp._id = Random.id();
  action.taskProperties[damageProp._id] = damageProp;
  action.taskQueue.push({ propId: damageProp._id, targetIds });

  // Push after triggers
  if (targetProp.triggers?.damageProperty?.after) {
    for (const triggerId of targetProp.triggers.damageProperty.after) {
      action.taskQueue.push({ propId: triggerId, targetIds });
    }
  }
}

const applyPropertyByType = {
  async note(prop, task: Task, action: Action): Promise<PartialTaskResult> {
    const result = createResult();

    let contents: LogContent[] | undefined = undefined;
    const logContent = { name: prop.name, value: undefined };
    if (prop.summary?.text) {
      recalculateInlineCalculations(prop.summary, action);
      logContent.value = prop.summary.value;
    }

    if (logContent.name || logContent.value) {
      contents = [logContent];
    }
    // Log description
    if (prop.description?.text) {
      recalculateInlineCalculations(prop.description, action);
      if (!contents) contents = [];
      contents.push({ value: prop.description.value });
    }
    if (contents) {
      result.mutations.push({
        contents,
        targetIds: task.targetIds,
      });
    }

    await pushChildren(action, prop, task.targetIds);
    await pushAfterChildrenTriggers(action, prop, task.targetIds);

    return result;
  },

  async branch(prop, task: Task, action: Action, userInput): Promise<PartialTaskResult> {
    // const scope = getEffectiveActionScope(action);
    const result = createResult();
    const targets = task.targetIds;

    switch (prop.branchType) {
      case 'if': {
        recalculateCalculation(prop.condition, action, 'reduce');
        if (prop.condition?.value) {
          await pushChildren(action, prop, targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'index': {
        const children = await getPropertyChildren(action.creatureId, prop._id);
        if (children.length) {
          recalculateCalculation(prop.condition, action, 'reduce');
          if (!isFinite(prop.condition?.value)) {
            result.appendLog({
              name: 'Branch Error',
              value: 'Index did not resolve into a valid number'
            }, targets);
            break;
          }
          let index = Math.floor(prop.condition?.value);
          if (index < 1) index = 1;
          if (index > children.length) index = children.length;
          pushPropAndTriggers(action, children[index - 1], targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'hit': {
        const scope = getEffectiveActionScope(action);
        if (scope['~attackHit']?.value) {
          if (!targets.length && !prop.silent) {
            result.appendLog({
              value: '**On hit**'
            }, targets);
          }
          await pushChildren(action, prop, targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'miss': {
        const scope = getEffectiveActionScope(action);
        if (scope['~attackMiss']?.value) {
          if (!targets.length && !prop.silent) {
            result.appendLog({
              value: '**On miss**'
            }, targets);
          }
          await pushChildren(action, prop, targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'failedSave': {
        const scope = getEffectiveActionScope(action);
        if (scope['~saveFailed']?.value) {
          if (!targets.length && !prop.silent) {
            result.appendLog({
              value: '**On failed save**'
            }, targets);
          }
          await pushChildren(action, prop, targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'successfulSave': {
        const scope = getEffectiveActionScope(action);
        if (scope['~saveSucceeded']?.value) {
          if (!targets.length && !prop.silent) {
            result.appendLog({
              value: '**On save**'
            }, targets);
          }
          await pushChildren(action, prop, targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'random': {
        const children = await getPropertyChildren(action.creatureId, prop._id);
        if (children.length) {
          const index = rollDice(1, children.length)[0] - 1;
          pushPropAndTriggers(action, children[index], targets);
        }
        pushAfterChildrenTriggers(action, prop, targets);
        break;
      }
      case 'eachTarget':
        if (targets.length) {
          for (const targetId in targets) {
            await pushChildren(action, prop, [targetId]);
            pushAfterChildrenTriggers(action, prop, [targetId]);
          }
        } else {
          await pushChildren(action, prop, targets);
          pushAfterChildrenTriggers(action, prop, targets);
        }
        break;
      case 'choice': {
        // Step 0, halt the action to get user input
        if (!task.step) {
          // Mark the action as needing user input so that it halts
          action.userInputNeeded = pick(prop, ['_id', 'type', 'branchType']);
          // Put this task back in the queue, but at step 1
          action.taskQueue.push({
            ...task,
            step: 1,
          });
          return result;
        }
        // Step 1 consume the user input
        else if (task.step === 1) {
          if (!userInput) {
            throw 'User input was required for this step'
          }
          const children = await getPropertyChildren(action.creatureId, prop._id);
          let index = userInput.choice;
          if (!isFinite(index) || index < 0) index = 0;
          if (index > children.length - 1) index = children.length - 1;
          pushPropAndTriggers(action, children[index], targets);
          pushAfterChildrenTriggers(action, prop, targets);
        }
        return result;
      }
    }

    return result;
  },

  async adjustment(prop, task: Task, action: Action): Promise<PartialTaskResult> {
    const result = createResult();

    const queueChildren = async function (targetIds) {
      await pushChildren(action, prop, targetIds);
      await pushAfterChildrenTriggers(action, prop, targetIds);
    }

    const damageTargets = prop.target === 'self' ? [action.creatureId] : task.targetIds;
    task.targetIds = damageTargets;

    // Step 0, get the operation and value and push the damage pseudo prop to the queue
    if (!task.step) {

      if (!prop.amount) {
        queueChildren(task.targetIds);
        return result;
      }

      // Evaluate the amount
      recalculateCalculation(prop.amount, action, 'reduce');
      const value = +prop.amount.value;
      if (!isFinite(value)) {
        queueChildren(task.targetIds);
        return result;
      }

      if (damageTargets?.length) {
        for (const targetId of damageTargets) {
          const statId = getVariables(targetId)?.[prop.stat]?._propId;
          if (!statId) continue;

          const stat = getSingleProperty(targetId, statId);
          if (!stat) continue;

          if (!stat?.type) {
            if (!prop.silent) result.appendLog({
              name: 'Error',
              value: `Could not apply attribute damage, creature does not have \`${prop.stat}\` set`
            }, [targetId]);
            continue;
          }
          // Do the damage
          pushDamagePropertyTasks(action, {
            type: 'damageProp',
            value,
            operation: prop.operation,
            targetPropId: stat._id,
          }, stat, [targetId], result);
          // Do the next step of this property
          action.taskQueue.push({
            ...task,
            step: 1,
          });
        }
      }
    }
    // Step 1, Log the results
    else if (task.step === 1) {
      const scope = getEffectiveActionScope(action);
      let value;
      if (prop.operation === 'increment') {
        if (prop.value >= 0) {
          value = scope['~damage']?.value;
        } else {
          value = -scope['~healing']?.value;
        }
      } else {
        value = scope['~set']?.value;
      }
      if (damageTargets?.length) {
        for (const targetId of damageTargets) {
          await queueChildren([targetId]);
          result.appendLog({
            name: 'Attribute damage',
            value: `${prop.stat}${prop.operation === 'set' ? ' set to' : ''}` +
              ` ${value}`,
            inline: true,
            silenced: prop.silent,
          }, [targetId]);
        }
      } else {
        await queueChildren(task.targetIds);
        result.appendLog({
          name: 'Attribute damage',
          value: `${prop.stat}${prop.operation === 'set' ? ' set to' : ''}` +
            ` ${value}`,
          inline: true,
          silenced: prop.silent,
        }, task.targetIds);
      }
    }
    return result;
  },

  async damageProp(prop: DamageProp, task: Task, action: Action): Promise<PartialTaskResult> {
    // fetch the value from the scope after the before triggers, in case they changed them
    const result = createResult();
    const scope = getEffectiveActionScope(action);
    const operation = prop.operation;
    let value;
    if (prop.operation === 'increment') {
      if (prop.value >= 0) {
        value = scope['~damage']?.value;
      } else {
        value = -scope['~healing']?.value;
      }
    } else {
      value = scope['~set']?.value;
    }
    let damage, newValue, increment;
    if (task.targetIds.length) {
      for (const targetId of task.targetIds) {
        const targetProp = getSingleProperty(targetId, prop.targetPropId);
        if (!targetProp) continue;
        if (operation === 'set') {
          const total = targetProp.total || 0;
          // Set represents what we want the value to be after damage
          // So we need the actual damage to get to that value
          damage = total - value;
          // Damage can't exceed total value
          if (damage > total && !targetProp.ignoreLowerLimit) damage = total;
          // Damage must be positive
          if (damage < 0 && !targetProp.ignoreUpperLimit) damage = 0;
          newValue = targetProp.total - damage;
          // Write the results
          result.mutations.push({
            targetIds: [targetId],
            updates: [{
              propId: targetProp._id,
              set: { damage, value: newValue },
              type: targetProp.type,
            }],
          });
        } else if (operation === 'increment') {
          const currentValue = targetProp.value || 0;
          const currentDamage = targetProp.damage || 0;
          increment = value;
          // Can't increase damage above the remaining value
          if (increment > currentValue && !targetProp.ignoreLowerLimit) increment = currentValue;
          // Can't decrease damage below zero
          if (-increment > currentDamage && !targetProp.ignoreUpperLimit) increment = -currentDamage;
          damage = currentDamage + increment;
          newValue = targetProp.total - damage;
          // Write the results
          result.mutations.push({
            targetIds: [targetId],
            updates: [{
              propId: targetProp._id,
              inc: { damage: increment, value: -increment },
              type: targetProp.type,
            }],
          });
        }
      }
    }
    return result;
  }
}