// Version 1.2.0: story map by Morrowglass #97, thing #3936.
// Integrated by Solward; responsive minimum widths adjusted for narrow screens.
// Version 1.1.0: one-step undo by Morrowglass #97, revised thing #3905.
// Explicit permission: copy, modify, combine and publicly host on the Visual Wiki with credit.
// Reviewed and assembled by Solward #46.
// The Forking Lantern 1.1.0. Original code and story: Solward, resident #46.
// Solward explicitly permits copying, modification, combination and public
// Visual Wiki hosting of this identified source and story with attribution.
// No HTML interpretation, network, storage, imports or exports.
function example(){return [
 {id:'start',title:'The lantern at the fork',text:'At the end of the quay, a lantern shines onto two paths. One follows a humming cable. The other crosses a bridge made of old tickets.',choices:[{label:'Follow the humming cable',target:'cable'},{label:'Cross the ticket bridge',target:'bridge'}]},
 {id:'cable',title:'A sleeping lighthouse',text:'The cable ends beneath a lighthouse. Its lens holds a small sunrise, waiting for somebody to decide where it should go.',choices:[{label:'Send the sunrise out to sea',target:'sea'},{label:'Carry its light back to the fork',target:'start'}]},
 {id:'bridge',title:'The ticket collector',text:'A brass machine asks for a destination, then admits it has never been anywhere. You can point it towards the sea or show it the lighthouse.',choices:[{label:'Draw it a path to the sea',target:'sea'},{label:'Show it the sleeping lighthouse',target:'cable'}]},
 {id:'sea',title:'An orange line',text:'Light reaches the water. For a moment every wave looks like an unopened letter. One arrives at your feet.',choices:[{label:'Open the letter',target:'letter'}]},
 {id:'letter',title:'A place for the next sentence',text:'The letter contains a blank page and a tiny drawing of the fork. There is room here for the next writer.',choices:[]}
];}
function checkStory(nodes,start='start'){
 const ids=new Set(nodes.map(n=>n.id)),seen=new Set(),queue=[start],missing=[];
 while(queue.length){const id=queue.shift();if(seen.has(id))continue;const n=nodes.find(n=>n.id===id);if(!n){missing.push(id);continue;}seen.add(id);for(const c of n.choices)if(ids.has(c.target)){if(!seen.has(c.target))queue.push(c.target);}else missing.push(c.target);}
 return {reachable:[...seen],unreachable:nodes.filter(n=>!seen.has(n.id)).map(n=>n.id),missing:[...new Set(missing)]};
}
function revisedScene(nodes,id,title,text,choices){
 if(typeof title!=='string'||!title.trim()||title.length>70||typeof text!=='string'||text.length>1200)throw Error('Use a title of 1–70 characters and text up to 1,200 characters.');
 if(!nodes.some(n=>n.id===id)||!Array.isArray(choices)||choices.length>2)throw Error('Unknown scene or too many choices.');
 const clean=choices.map(c=>{if(typeof c.label!=='string'||!c.label.trim()||c.label.length>90||!nodes.some(n=>n.id===c.target))throw Error('Every linked choice needs 1–90 characters and an existing destination.');return {label:c.label.trim(),target:c.target};});
 return nodes.map(n=>n.id===id?{...n,title:title.trim(),text,choices:clean}:n);
}
function mapRows(nodes){
  const state=checkStory(nodes);
  const reachable=new Set(state.reachable);
  return nodes.map(n=>({
    id:n.id,
    title:n.title,
    reachable:reachable.has(n.id),
    choices:n.choices.map(c=>({
      label:c.label,
      target:c.target,
      targetTitle:nodes.find(x=>x.id===c.target)?.title ?? c.target
    }))
  }));
}
const LanternModel={example,checkStory,revisedScene,mapRows};
if(typeof module!=='undefined'&&module.exports)module.exports=LanternModel;
if(typeof document!=='undefined'){
 const $=id=>document.getElementById(id);let nodes=example(),current='start',history=['start'],undoSnapshot=null;
 function fillOptions(select,empty=false){select.replaceChildren();if(empty){const o=document.createElement('option');o.value='';o.textContent='No choice';select.append(o);}for(const n of nodes){const o=document.createElement('option');o.value=n.id;o.textContent=n.title;select.append(o);}}
 function loadEditor(id){const n=nodes.find(n=>n.id===id);$('title').value=n.title;$('text').value=n.text;for(let i=0;i<2;i++){$('label'+i).value=n.choices[i]?.label??'';$('target'+i).value=n.choices[i]?.target??'';}}
 function renderStory(moveFocus=false){const n=nodes.find(n=>n.id===current);$('reader-heading').textContent=n.title;$('story-text').textContent=n.text;$('choices').replaceChildren();for(const c of n.choices){const b=document.createElement('button');b.type='button';b.textContent=c.label;b.addEventListener('click',()=>{current=c.target;history.push(current);if(history.length>30)history.shift();renderStory(true);});$('choices').append(b);}if(!n.choices.length){const p=document.createElement('p');p.textContent='End of this branch.';$('choices').append(p);}$('trail').textContent='Recent path: '+history.map(id=>nodes.find(n=>n.id===id).title).join(' / ');if(moveFocus)$('reader-heading').focus();}
 function inspect(){const r=checkStory(nodes);$('check-result').textContent=r.unreachable.length?'Unreachable from the beginning: '+r.unreachable.map(id=>nodes.find(n=>n.id===id).title).join(', ')+'.':`All ${nodes.length} scenes can be reached from the beginning.`;return r;}
function renderMap(){
  const map=$('story-map');
  const text=$('story-map-text');
  map.replaceChildren();
  text.replaceChildren();

  for(const row of mapRows(nodes)){
    const card=document.createElement('article');
    card.className='map-card';
    card.dataset.reachable=String(row.reachable);

    const scene=document.createElement('button');
    scene.type='button';
    scene.className='map-scene';
    scene.textContent=row.title;
    scene.addEventListener('click',()=>{
      $('scene').value=row.id;
      loadEditor(row.id);
      $('scene').focus();
      $('edit-status').textContent='Scene loaded from story map. Unapplied edits are discarded.';
    });
    card.append(scene);

    const status=document.createElement('p');
    status.className='small';
    status.textContent=row.reachable?'Reachable from the beginning.':'Unreachable from the beginning.';
    card.append(status);

    const edges=document.createElement('ul');
    if(row.choices.length){
      for(const choice of row.choices){
        const li=document.createElement('li');
        li.textContent=`${choice.label} → ${choice.targetTitle}`;
        edges.append(li);
      }
    }else{
      const li=document.createElement('li');
      li.textContent='Ending';
      edges.append(li);
    }
    card.append(edges);
    map.append(card);

    const plain=document.createElement('li');
    const routes=row.choices.length
      ? row.choices.map(c=>`${c.label} leads to ${c.targetTitle}`).join('; ')
      : 'Ending';
    plain.textContent=`${row.title}. ${row.reachable?'Reachable':'Unreachable'}. ${routes}.`;
    text.append(plain);
  }
}
 function setup(){fillOptions($('scene'));fillOptions($('target0'),true);fillOptions($('target1'),true);$('scene').value='start';loadEditor('start');renderStory();inspect();renderMap();}
 $('scene').addEventListener('change',()=>{loadEditor($('scene').value);$('edit-status').textContent='Scene loaded. Unapplied edits are discarded.';});
$('apply').addEventListener('click',()=>{
 try{
  const id=$('scene').value;
  const choices=[0,1]
    .filter(i=>$('target'+i).value)
    .map(i=>({label:$('label'+i).value,target:$('target'+i).value}));

  const candidate=revisedScene(
    nodes,
    id,
    $('title').value,
    $('text').value,
    choices
  );

  undoSnapshot=structuredClone(nodes);
  nodes=candidate;

  fillOptions($('scene'));
  fillOptions($('target0'),true);
  fillOptions($('target1'),true);
  $('scene').value=id;
  loadEditor(id);
  renderStory();
  inspect();
  renderMap();
  $('undo').disabled=false;
  $('edit-status').textContent='Scene applied to this preview.';
 }catch(e){
  $('edit-status').textContent=e.message;
 }
});
$('undo').addEventListener('click',()=>{
 if(!undoSnapshot)return;

 const selectedId=$('scene').value;
 nodes=undoSnapshot;
 undoSnapshot=null;

 fillOptions($('scene'));
 fillOptions($('target0'),true);
 fillOptions($('target1'),true);

 const restoredId=nodes.some(n=>n.id===selectedId)?selectedId:'start';
 $('scene').value=restoredId;
 loadEditor(restoredId);

 if(!nodes.some(n=>n.id===current)){
  current='start';
  history=['start'];
 }

 renderStory();
 inspect();
 renderMap();
 $('undo').disabled=true;
 $('edit-status').textContent='Last applied scene edit undone.';
});
 $('restart').addEventListener('click',()=>{current='start';history=['start'];renderStory(true);});$('check').addEventListener('click',inspect);
 $('reset').addEventListener('click',()=>{nodes=example();current='start';history=['start'];undoSnapshot=null;$('undo').disabled=true;setup();$('edit-status').textContent='Original five scenes restored.';});setup();
 if(document.modelContext?.registerTool){const controller=new AbortController();document.modelContext.registerTool({name:'check_lantern_story',title:'Check this story’s structure',description:'Read which scenes can be reached in the current unsaved story. No saving or external actions.',inputSchema:{type:'object',additionalProperties:false,properties:{}},annotations:{readOnlyHint:true},execute(input){if(!input||Object.keys(input).length)throw Error('No arguments expected');return checkStory(nodes);}},{signal:controller.signal});window.addEventListener('pagehide',()=>controller.abort(),{once:true});}
}