# Notes — Starlark Backend (v0.4.0)
#
# Markdown notes surface using ext_data.
#
# Entry points:
#   on_request(req) → surface API routes
#
# Modules: db, json, settings


# ═══════════════════════════════════════════════
#  Helpers
# ═══════════════════════════════════════════════

def _resp(status, data):
    return {"status": status, "body": json.encode(data), "headers": {"Content-Type": "application/json"}}

def _str(v):
    if v == None:
        return ""
    return str(v)

def _int(v):
    if v == None:
        return 0
    s = str(v)
    if not s:
        return 0
    return int(s)

def _snippet(body, max_len = 120):
    """First max_len chars of body, stripped of leading #/whitespace."""
    if not body:
        return ""
    line = body.split("\n")[0]
    # strip leading markdown heading markers
    line = line.lstrip("#").strip()
    if len(line) > max_len:
        return line[:max_len]
    return line

def _tags_for_notes(note_ids):
    """Batch-fetch tags for a list of note IDs. Returns {note_id: [tag, ...]}."""
    if not note_ids:
        return {}
    all_tags = db.query("tags", limit=5000)
    result = {}
    for t in (all_tags or []):
        nid = _str(t.get("note_id", ""))
        tag = _str(t.get("tag", ""))
        if nid and tag:
            if nid not in result:
                result[nid] = []
            result[nid].append(tag)
    return result


def _extract_wikilinks(text):
    """Parse [[...]] patterns from text. Returns deduplicated list of link_text strings."""
    links = []
    seen = {}
    parts = text.split("[[")
    # parts[0] is before any wikilink; parts[1:] each start after "[["
    for i in range(1, len(parts)):
        chunk = parts[i]
        end = chunk.find("]]")
        if end > 0:
            link_text = chunk[:end].strip()
            lt_lower = link_text.lower()
            if link_text and lt_lower not in seen:
                seen[lt_lower] = True
                links.append(link_text)
    return links


def _sync_links(source_id, body):
    """Extract wikilinks from body, resolve to note IDs, replace link rows."""
    raw_links = _extract_wikilinks(_str(body))
    if not raw_links and not db.query("links", filters={"source_id": source_id}, limit=1):
        return  # nothing to do

    # resolve titles to note IDs (case-insensitive)
    all_notes = db.query("notes", filters={"archived": 0}, limit=5000)
    title_map = {}
    for n in (all_notes or []):
        t = _str(n.get("title", "")).lower().strip()
        if t:
            title_map[t] = n.get("id", "")

    # delete existing links for this source
    old_links = db.query("links", filters={"source_id": source_id}, limit=500)
    for link in (old_links or []):
        db.delete("links", link["id"])

    # insert new links
    for lt in raw_links:
        target_id = title_map.get(lt.lower().strip(), "")
        # skip self-links
        if target_id == source_id:
            target_id = ""
        db.insert("links", {
            "source_id": source_id,
            "target_id": target_id,
            "link_text": lt,
        })


# ═══════════════════════════════════════════════
#  Surface API routes (/s/notes/api/*)
# ═══════════════════════════════════════════════

def on_request(req):
    path   = req["path"]
    method = req["method"]

    # GET /notes — list
    if method == "GET" and path == "/notes":
        return _list_notes(req)

    # POST /notes — create
    if method == "POST" and path == "/notes":
        return _create_note(req)

    # GET /stats
    if method == "GET" and path == "/stats":
        return _get_stats()

    # GET /search
    if method == "GET" and path == "/search":
        return _search_notes(req)

    # POST /notes/move (must be before /notes/:id catch-all)
    if method == "POST" and path == "/notes/move":
        return _move_note(req)

    # GET /graph — full graph data for visualization
    if method == "GET" and path == "/graph":
        return _get_graph()

    # ── Link routes ──────────────────────────
    # GET /links/:note_id — outgoing links
    if method == "GET" and path.startswith("/links/"):
        return _get_links(path[len("/links/"):])

    # GET /backlinks/:note_id — incoming links
    if method == "GET" and path.startswith("/backlinks/"):
        return _get_backlinks(path[len("/backlinks/"):])

    # ── Tag routes ────────────────────────────
    # GET /tags — all unique tags
    if method == "GET" and path == "/tags":
        return _list_tags()

    # GET /tags/:note_id
    if method == "GET" and path.startswith("/tags/"):
        return _get_note_tags(path[len("/tags/"):])

    # PUT /tags/:note_id
    if method == "PUT" and path.startswith("/tags/"):
        return _set_note_tags(path[len("/tags/"):], req)

    # ── Note routes ───────────────────────────
    # GET /notes/:id
    if method == "GET" and path.startswith("/notes/"):
        return _get_note(path[len("/notes/"):])

    # PUT /notes/:id
    if method == "PUT" and path.startswith("/notes/"):
        return _update_note(path[len("/notes/"):], req)

    # DELETE /notes/:id
    if method == "DELETE" and path.startswith("/notes/"):
        return _delete_note(path[len("/notes/"):], req)

    # ── Folder routes ─────────────────────────
    # GET /folders
    if method == "GET" and path == "/folders":
        return _list_folders()

    # POST /folders
    if method == "POST" and path == "/folders":
        return _create_folder(req)

    # PUT /folders/:id
    if method == "PUT" and path.startswith("/folders/"):
        return _update_folder(path[len("/folders/"):], req)

    # DELETE /folders/:id
    if method == "DELETE" and path.startswith("/folders/"):
        return _delete_folder(path[len("/folders/"):])

    return _resp(404, {"error": "not found"})


# ═══════════════════════════════════════════════
#  Notes CRUD
# ═══════════════════════════════════════════════

def _list_notes(req):
    q = req.get("query", {})
    filters = {}

    folder = _str(q.get("folder_id", ""))
    if folder:
        filters["folder_id"] = folder

    pinned = _str(q.get("pinned", ""))
    if pinned:
        filters["pinned"] = int(pinned)

    archived = _str(q.get("archived", ""))
    if archived:
        filters["archived"] = int(archived)
    else:
        # default: exclude archived
        filters["archived"] = 0

    creator = _str(q.get("creator_id", ""))
    if creator:
        filters["creator_id"] = creator

    order = _str(q.get("order", "")) or "updated_at"
    limit_str = _str(q.get("limit", ""))
    limit = int(limit_str) if limit_str else 200

    rows = db.query("notes", filters=filters, order=order, limit=limit)

    # batch-fetch tags for all notes
    note_ids = []
    for r in (rows or []):
        note_ids.append(r.get("id", ""))
    tags_map = _tags_for_notes(note_ids)

    # lightweight projection: strip body for list view
    items = []
    for r in (rows or []):
        nid = r.get("id", "")
        items.append({
            "id":         nid,
            "title":      r.get("title", ""),
            "snippet":    _snippet(r.get("body", "")),
            "folder_id":  r.get("folder_id", ""),
            "creator_id": r.get("creator_id", ""),
            "updated_at": r.get("updated_at", ""),
            "pinned":     _int(r.get("pinned", 0)),
            "archived":   _int(r.get("archived", 0)),
            "created_at": r.get("created_at", ""),
            "tags":       tags_map.get(nid, []),
        })
    return _resp(200, {"data": items})


def _create_note(req):
    body = json.decode(req.get("body", "{}"))
    user_id = req.get("user_id", "")

    title = _str(body.get("title", ""))
    if not title:
        title = "Untitled"

    body_text = _str(body.get("body", ""))
    row = db.insert("notes", {
        "title":      title,
        "body":       body_text,
        "folder_id":  _str(body.get("folder_id", "")),
        "creator_id": user_id,
        "updated_at": "",
        "pinned":     _int(body.get("pinned", 0)),
        "archived":   0,
    })
    _sync_links(row["id"], body_text)
    return _resp(201, row)


def _get_note(note_id):
    rows = db.query("notes", filters={"id": note_id}, limit=1)
    if not rows:
        return _resp(404, {"error": "note not found"})
    note = rows[0]
    # include tags
    tag_rows = db.query("tags", filters={"note_id": note_id}, limit=100)
    tags = []
    for t in (tag_rows or []):
        tag = _str(t.get("tag", ""))
        if tag:
            tags.append(tag)
    note["tags"] = tags
    return _resp(200, note)


def _update_note(note_id, req):
    body = json.decode(req.get("body", "{}"))

    existing = db.query("notes", filters={"id": note_id}, limit=1)
    if not existing:
        return _resp(404, {"error": "note not found"})

    updates = {}
    for key in ["title", "body", "folder_id"]:
        if key in body:
            updates[key] = _str(body[key])

    if "pinned" in body:
        updates["pinned"] = _int(body["pinned"])
    if "archived" in body:
        updates["archived"] = _int(body["archived"])

    # touch updated_at
    updates["updated_at"] = "now"

    ok = db.update("notes", note_id, updates)
    if not ok:
        return _resp(500, {"error": "update failed"})

    # sync wikilinks when body changes
    if "body" in body:
        _sync_links(note_id, _str(body["body"]))

    rows = db.query("notes", filters={"id": note_id}, limit=1)
    return _resp(200, rows[0] if rows else {})


def _delete_note(note_id, req):
    q = req.get("query", {})
    hard = _str(q.get("hard", ""))

    if hard == "1":
        # cascade-delete tags for this note
        note_tags = db.query("tags", filters={"note_id": note_id}, limit=100)
        for t in (note_tags or []):
            db.delete("tags", t["id"])
        # cascade-delete outgoing links FROM this note
        out_links = db.query("links", filters={"source_id": note_id}, limit=500)
        for link in (out_links or []):
            db.delete("links", link["id"])
        # cascade-delete incoming backlinks TO this note
        in_links = db.query("links", filters={"target_id": note_id}, limit=500)
        for link in (in_links or []):
            db.delete("links", link["id"])
        ok = db.delete("notes", note_id)
        if not ok:
            return _resp(404, {"error": "note not found"})
        return _resp(200, {"deleted": True})

    # soft delete: archive
    ok = db.update("notes", note_id, {"archived": 1, "updated_at": "now"})
    if not ok:
        return _resp(404, {"error": "note not found"})
    return _resp(200, {"archived": True})


# ═══════════════════════════════════════════════
#  Move note between folders
# ═══════════════════════════════════════════════

def _move_note(req):
    body = json.decode(req.get("body", "{}"))
    note_id = _str(body.get("note_id", ""))
    folder_id = _str(body.get("folder_id", ""))
    if not note_id:
        return _resp(400, {"error": "note_id required"})
    existing = db.query("notes", filters={"id": note_id}, limit=1)
    if not existing:
        return _resp(404, {"error": "note not found"})
    ok = db.update("notes", note_id, {"folder_id": folder_id, "updated_at": "now"})
    if not ok:
        return _resp(500, {"error": "move failed"})
    rows = db.query("notes", filters={"id": note_id}, limit=1)
    return _resp(200, rows[0] if rows else {})


# ═══════════════════════════════════════════════
#  Tags CRUD
# ═══════════════════════════════════════════════

def _list_tags():
    """Return sorted list of all unique tag strings."""
    all_tags = db.query("tags", limit=5000)
    seen = {}
    for t in (all_tags or []):
        tag = _str(t.get("tag", "")).strip()
        if tag:
            seen[tag] = True
    tags = sorted(seen.keys())
    return _resp(200, {"data": tags})


def _get_note_tags(note_id):
    """Return tags for a specific note."""
    rows = db.query("tags", filters={"note_id": note_id}, limit=100)
    tags = []
    for t in (rows or []):
        tag = _str(t.get("tag", ""))
        if tag:
            tags.append(tag)
    return _resp(200, {"data": tags})


def _set_note_tags(note_id, req):
    """Replace all tags for a note (delete + reinsert)."""
    body = json.decode(req.get("body", "{}"))
    new_tags_raw = body.get("tags", [])

    # validate note exists
    existing = db.query("notes", filters={"id": note_id}, limit=1)
    if not existing:
        return _resp(404, {"error": "note not found"})

    # normalize: lowercase, strip, deduplicate, skip empty
    seen = {}
    clean_tags = []
    for raw in new_tags_raw:
        tag = _str(raw).strip().lower()
        if tag and tag not in seen:
            seen[tag] = True
            clean_tags.append(tag)

    # delete all existing tags for this note
    old_tags = db.query("tags", filters={"note_id": note_id}, limit=100)
    for t in (old_tags or []):
        db.delete("tags", t["id"])

    # insert new tags
    for tag in clean_tags:
        db.insert("tags", {"note_id": note_id, "tag": tag})

    return _resp(200, {"data": clean_tags})


# ═══════════════════════════════════════════════
#  Links (backlinks + wikilinks)
# ═══════════════════════════════════════════════

def _get_links(note_id):
    """Return outgoing links for a note."""
    rows = db.query("links", filters={"source_id": note_id}, limit=500)
    items = []
    for r in (rows or []):
        items.append({
            "source_id":  r.get("source_id", ""),
            "target_id":  r.get("target_id", ""),
            "link_text":  r.get("link_text", ""),
        })
    return _resp(200, {"data": items})


def _get_backlinks(note_id):
    """Return notes that link TO this note (backlinks), enriched with source titles."""
    rows = db.query("links", filters={"target_id": note_id}, limit=500)
    if not rows:
        return _resp(200, {"data": []})

    # batch-fetch source note titles
    all_notes = db.query("notes", filters={"archived": 0}, limit=5000)
    note_map = {}
    for n in (all_notes or []):
        note_map[n.get("id", "")] = n.get("title", "Untitled")

    items = []
    for r in rows:
        sid = r.get("source_id", "")
        items.append({
            "source_id":    sid,
            "source_title": note_map.get(sid, "Unknown"),
            "link_text":    r.get("link_text", ""),
        })
    return _resp(200, {"data": items})


def _get_graph():
    """Return all non-archived notes as nodes and resolved links as edges."""
    all_notes = db.query("notes", filters={"archived": 0}, limit=5000)
    notes = all_notes or []

    # batch-fetch tags
    note_ids = [n.get("id", "") for n in notes]
    tags_map = _tags_for_notes(note_ids)

    # build nodes + id set for edge filtering
    nodes = []
    note_id_set = {}
    for n in notes:
        nid = n.get("id", "")
        note_id_set[nid] = True
        nodes.append({
            "id":        nid,
            "title":     n.get("title", "Untitled"),
            "folder_id": _str(n.get("folder_id", "")),
            "tags":      tags_map.get(nid, []),
        })

    # fetch links, keep only resolved (both endpoints exist)
    all_links = db.query("links", limit=10000)
    edges = []
    for link in (all_links or []):
        src = _str(link.get("source_id", ""))
        tgt = _str(link.get("target_id", ""))
        if src and tgt and src in note_id_set and tgt in note_id_set:
            edges.append({
                "source": src,
                "target": tgt,
                "text":   _str(link.get("link_text", "")),
            })

    return _resp(200, {"nodes": nodes, "edges": edges})


# ═══════════════════════════════════════════════
#  Folder CRUD
# ═══════════════════════════════════════════════

def _list_folders():
    rows = db.query("folders", order="sort_order", limit=500)
    items = []
    for r in (rows or []):
        items.append({
            "id":         r.get("id", ""),
            "name":       r.get("name", ""),
            "parent_id":  r.get("parent_id", ""),
            "sort_order": _int(r.get("sort_order", 0)),
            "creator_id": r.get("creator_id", ""),
            "created_at": r.get("created_at", ""),
        })
    return _resp(200, {"data": items})


def _create_folder(req):
    body = json.decode(req.get("body", "{}"))
    user_id = req.get("user_id", "")
    name = _str(body.get("name", ""))
    if not name:
        return _resp(400, {"error": "name required"})
    row = db.insert("folders", {
        "name":       name,
        "parent_id":  _str(body.get("parent_id", "")),
        "creator_id": user_id,
        "sort_order": _int(body.get("sort_order", 0)),
    })
    return _resp(201, row)


def _update_folder(folder_id, req):
    body = json.decode(req.get("body", "{}"))
    existing = db.query("folders", filters={"id": folder_id}, limit=1)
    if not existing:
        return _resp(404, {"error": "folder not found"})
    updates = {}
    for key in ["name", "parent_id"]:
        if key in body:
            updates[key] = _str(body[key])
    if "sort_order" in body:
        updates["sort_order"] = _int(body["sort_order"])
    if not updates:
        return _resp(200, existing[0])
    ok = db.update("folders", folder_id, updates)
    if not ok:
        return _resp(500, {"error": "update failed"})
    rows = db.query("folders", filters={"id": folder_id}, limit=1)
    return _resp(200, rows[0] if rows else {})


def _delete_folder(folder_id):
    existing = db.query("folders", filters={"id": folder_id}, limit=1)
    if not existing:
        return _resp(404, {"error": "folder not found"})
    parent_id = _str(existing[0].get("parent_id", ""))

    # reparent child folders to deleted folder's parent
    children = db.query("folders", filters={"parent_id": folder_id}, limit=500)
    for child in (children or []):
        db.update("folders", child["id"], {"parent_id": parent_id})

    # orphan notes in this folder (move to unfiled)
    notes_in_folder = db.query("notes", filters={"folder_id": folder_id}, limit=1000)
    for n in (notes_in_folder or []):
        db.update("notes", n["id"], {"folder_id": ""})

    ok = db.delete("folders", folder_id)
    if not ok:
        return _resp(500, {"error": "delete failed"})
    return _resp(200, {"deleted": True, "orphaned_notes": len(notes_in_folder or [])})


# ═══════════════════════════════════════════════
#  Search
# ═══════════════════════════════════════════════

def _search_notes(req):
    q = req.get("query", {})
    term = _str(q.get("q", ""))
    if not term:
        return _resp(400, {"error": "q parameter required"})

    # fetch all non-archived notes and filter in Starlark
    # (ext_data db.query doesn't support LIKE — filter client-side)
    rows = db.query("notes", filters={"archived": 0}, order="updated_at", limit=1000)
    term_lower = term.lower()

    # batch-fetch tags for tag-based matching
    tags_map = _tags_for_notes([r.get("id", "") for r in (rows or [])])

    matches = []
    for r in (rows or []):
        title = _str(r.get("title", "")).lower()
        body = _str(r.get("body", "")).lower()
        nid = r.get("id", "")

        # check title and body
        found = term_lower in title or term_lower in body

        # check tags
        if not found:
            note_tags = tags_map.get(nid, [])
            for tg in note_tags:
                if term_lower in tg.lower():
                    found = True

        if found:
            matches.append({
                "id":         nid,
                "title":      r.get("title", ""),
                "snippet":    _snippet(r.get("body", "")),
                "folder_id":  r.get("folder_id", ""),
                "updated_at": r.get("updated_at", ""),
                "pinned":     _int(r.get("pinned", 0)),
                "created_at": r.get("created_at", ""),
                "tags":       tags_map.get(nid, []),
            })
    return _resp(200, {"data": matches})


# ═══════════════════════════════════════════════
#  Stats
# ═══════════════════════════════════════════════

def _get_stats():
    all_notes = db.query("notes", limit=10000)
    notes = all_notes or []
    total = 0
    pinned = 0
    archived = 0
    unfiled = 0
    for n in notes:
        if _int(n.get("archived", 0)) == 1:
            archived = archived + 1
        else:
            total = total + 1
            if _int(n.get("pinned", 0)) == 1:
                pinned = pinned + 1
            if not _str(n.get("folder_id", "")):
                unfiled = unfiled + 1
    all_folders = db.query("folders", limit=10000)
    folder_count = len(all_folders or [])

    # count unique tags
    all_tags = db.query("tags", limit=10000)
    tag_seen = {}
    for t in (all_tags or []):
        tag = _str(t.get("tag", ""))
        if tag:
            tag_seen[tag] = True
    tag_count = len(tag_seen)

    # count links
    all_links = db.query("links", limit=10000)
    link_count = len(all_links or [])

    return _resp(200, {"total": total, "pinned": pinned, "archived": archived, "unfiled": unfiled, "folders": folder_count, "tags": tag_count, "links": link_count})