import { MODULE_ID, SETTINGS } from "../constants.js";

const ASSIGNED_REACTIONS_FLAG = "assignedReactions";
const MANAGED_FEATURE_FLAG = "managedAssignmentFeature";
const FEATURE_TYPE = "feat";

export async function assignReactionToSelectedTokens(reactionId) {
  if (!game.user.isGM) {
    ui.notifications.warn(game.i18n.localize("CONFIGURABLE_REACTIONS.Errors.GmOnly"));
    return;
  }

  if (!reactionId) {
    ui.notifications.warn(game.i18n.localize("CONFIGURABLE_REACTIONS.Errors.NoReactionSelected"));
    return;
  }

  const selectedTokens = canvas?.tokens?.controlled ?? [];
  if (!selectedTokens.length) {
    ui.notifications.warn(game.i18n.localize("CONFIGURABLE_REACTIONS.Errors.NoTokensSelected"));
    return;
  }

  const reactions = game.settings.get(MODULE_ID, SETTINGS.REACTIONS) ?? [];
  const reaction = reactions.find(candidate => candidate.id === reactionId);
  if (!reaction) {
    ui.notifications.error(game.i18n.localize("CONFIGURABLE_REACTIONS.Errors.ReactionNotFound"));
    return;
  }

  const assignments = foundry.utils.deepClone(game.settings.get(MODULE_ID, SETTINGS.ASSIGNMENTS) ?? []);
  let assignedCount = 0;
  let skippedCount = 0;

  for (const token of selectedTokens) {
    const result = await assignReactionToToken({ token, reaction, reactionId, assignments });
    if (result === "assigned") assignedCount++;
    else skippedCount++;
  }

  await game.settings.set(MODULE_ID, SETTINGS.ASSIGNMENTS, assignments);
  ui.notifications.info(game.i18n.format("CONFIGURABLE_REACTIONS.Assignments.AssignedResult", { assigned: assignedCount, skipped: skippedCount }));
}

async function assignReactionToToken({ token, reaction, reactionId, assignments }) {
  const tokenDocument = token?.document;
  const actor = token?.actor;
  if (!tokenDocument || !actor) return "skipped";

  const assignment = buildAssignmentForToken(tokenDocument, actor, reactionId);
  if (hasAssignment(assignments, assignment)) return "skipped";

  assignments.push(assignment);

  if (assignment.mode === "actor") {
    await addReactionFlag(actor, reactionId);
    await ensureManagedReactionFeature(actor, reaction);
    return "assigned";
  }

  await addReactionFlag(tokenDocument, reactionId);
  await ensureManagedReactionFeature(actor, reaction, tokenDocument.uuid);
  return "assigned";
}

function hasAssignment(assignments, assignment) {
  return assignments.some(existing =>
    existing.reactionId === assignment.reactionId &&
    existing.mode === assignment.mode &&
    existing.actorUuid === assignment.actorUuid &&
    existing.tokenUuid === assignment.tokenUuid
  );
}

export async function removeAssignment(assignmentId) {
  if (!game.user.isGM) return;

  const assignments = foundry.utils.deepClone(game.settings.get(MODULE_ID, SETTINGS.ASSIGNMENTS) ?? []);
  const assignment = assignments.find(candidate => candidate.id === assignmentId);
  if (!assignment) return;

  await game.settings.set(MODULE_ID, SETTINGS.ASSIGNMENTS, assignments.filter(candidate => candidate.id !== assignmentId));
  await removeAssignmentMarkers(assignment);
}

async function removeAssignmentMarkers(assignment) {
  if (assignment.mode === "actor" && assignment.actorUuid) {
    const actor = await fromUuid(assignment.actorUuid);
    if (actor) await removeReactionFromDocument(actor, assignment.reactionId, true);
    return;
  }

  if (assignment.mode !== "token" || !assignment.tokenUuid) return;

  const tokenDocument = await fromUuid(assignment.tokenUuid);
  if (!tokenDocument) return;

  await removeReactionFromDocument(tokenDocument, assignment.reactionId, false);
  if (tokenDocument.actor) await removeReactionFromDocument(tokenDocument.actor, assignment.reactionId, true, tokenDocument.uuid);
}

function buildAssignmentForToken(tokenDocument, actor, reactionId) {
  if (tokenDocument.actorLink === true) {
    return {
      id: foundry.utils.randomID(),
      reactionId,
      mode: "actor",
      actorUuid: actor.uuid,
      tokenUuid: null,
      sceneUuid: null,
      name: actor.name
    };
  }

  return {
    id: foundry.utils.randomID(),
    reactionId,
    mode: "token",
    actorUuid: null,
    tokenUuid: tokenDocument.uuid,
    sceneUuid: tokenDocument.parent?.uuid ?? canvas.scene?.uuid ?? null,
    name: tokenDocument.name
  };
}

async function addReactionFlag(document, reactionId) {
  const assigned = foundry.utils.deepClone(document.getFlag(MODULE_ID, ASSIGNED_REACTIONS_FLAG) ?? []);
  if (!assigned.some(entry => entry.reactionId === reactionId)) {
    assigned.push({ reactionId, assignedAt: Date.now(), assignedBy: game.user.id });
  }
  await document.setFlag(MODULE_ID, ASSIGNED_REACTIONS_FLAG, assigned);
}

async function ensureManagedReactionFeature(actor, reaction, tokenUuid = null) {
  if (!game.settings.get(MODULE_ID, SETTINGS.CREATE_MANAGED_EFFECTS_ON_ASSIGNMENT)) return;
  if (!actor?.createEmbeddedDocuments) return;
  if (findManagedReactionFeature(actor, reaction.id, tokenUuid)) return;

  await actor.createEmbeddedDocuments("Item", [buildManagedReactionFeatureData(reaction, tokenUuid)]);
}

function findManagedReactionFeature(actor, reactionId, tokenUuid = null) {
  return actor.items?.find(item =>
    item.type === FEATURE_TYPE &&
    item.getFlag(MODULE_ID, "reactionId") === reactionId &&
    item.getFlag(MODULE_ID, MANAGED_FEATURE_FLAG) === true &&
    (tokenUuid === null || item.getFlag(MODULE_ID, "tokenUuid") === tokenUuid)
  );
}

function buildManagedReactionFeatureData(reaction, tokenUuid = null) {
  const name = game.i18n.format("CONFIGURABLE_REACTIONS.Effects.ManagedReaction", { name: reaction.name });
  return {
    name,
    type: FEATURE_TYPE,
    img: reaction.icon ?? "icons/svg/aura.svg",
    system: {
      description: {
        value: `<p>${name}</p>`,
        chat: ""
      }
    },
    flags: {
      [MODULE_ID]: {
        reactionId: reaction.id,
        managed: true,
        [MANAGED_FEATURE_FLAG]: true,
        tokenUuid
      }
    }
  };
}

async function removeReactionFromDocument(document, reactionId, removeManagedFeature, tokenUuid = null) {
  const assigned = foundry.utils.deepClone(document.getFlag(MODULE_ID, ASSIGNED_REACTIONS_FLAG) ?? [])
    .filter(entry => entry.reactionId !== reactionId);

  if (assigned.length) await document.setFlag(MODULE_ID, ASSIGNED_REACTIONS_FLAG, assigned);
  else await document.unsetFlag(MODULE_ID, ASSIGNED_REACTIONS_FLAG);

  if (removeManagedFeature) await removeManagedReactionFeatures(document, reactionId, tokenUuid);
}

async function removeManagedReactionFeatures(actor, reactionId, tokenUuid = null) {
  const itemIds = actor.items
    ?.filter(item =>
      item.getFlag(MODULE_ID, "reactionId") === reactionId &&
      item.getFlag(MODULE_ID, MANAGED_FEATURE_FLAG) === true &&
      (tokenUuid === null || item.getFlag(MODULE_ID, "tokenUuid") === tokenUuid)
    )
    .map(item => item.id) ?? [];

  if (itemIds.length) await actor.deleteEmbeddedDocuments("Item", itemIds);
}