"""Task agent — full CRUD for tasks and task comments."""

from __future__ import annotations

from datetime import datetime, timezone
import re
from typing import Any

from langchain_core.tools import tool

from app.core.ws_context import execute_on_client

_UUID_RE = re.compile(
    r"^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-5][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}$"
)


def _is_uuid(value: str) -> bool:
    return bool(_UUID_RE.match(value))


# ── Task tools ────────────────────────────────────────────────────────


@tool
async def list_tasks(
    project_id: str = "",
    status: str = "",
    priority: str = "",
    assignee: str = "",
    search: str = "",
    order_by: str = "",
    order_dir: str = "",
    due_date_from: int = -1,
    due_date_to: int = -1,
    created_at_from: int = -1,
    created_at_to: int = -1,
    completed_at_from: int = -1,
    completed_at_to: int = -1,
    is_ai_suggested: int = -1,
    limit: int = 50,
    offset: int = 0,
) -> str:
    """List tasks with optional filters. Returns up to `limit` results (default 50).

    project_id: UUID of the project to scope results to.
    status: filter by status — todo | in_progress | done.
    priority: filter by priority — high | medium | low.
    assignee: substring to match against assignee names.
    search: substring search across title and description.
    order_by: sort field — dueDate | priority | createdAt | completedAt.
    order_dir: asc (default) | desc.
    due_date_from / due_date_to: ms epoch range for dueDate. Use -1 to omit.
    created_at_from / created_at_to: ms epoch range for createdAt. Use -1 to omit.
    completed_at_from / completed_at_to: ms epoch range for completedAt. Use -1 to omit.
    is_ai_suggested: 0 or 1 to filter by AI-suggested flag; -1 = any.
    limit: max rows to return (default 50). Use with offset to paginate.
    offset: skip first N rows (default 0).

    Tip — combine *_from and *_to for a closed range; pass only one for open-ended.
    Tip — prefer count_tasks for "how many" questions to avoid listing rows.
    Tip — for natural-language windows ("today", "tomorrow", "this week", "last month", etc.)
    take due_date_from / due_date_to verbatim from the DATE CONTEXT block in the system prompt;
    do not compute boundaries from the current UTC instant.
    """
    normalized_project_id = project_id if (project_id and _is_uuid(project_id)) else ""
    filters: dict[str, Any] = {
        "projectId": normalized_project_id or None,
        "status": status or None,
        "priority": priority or None,
        "search": search or None,
        "orderBy": order_by or None,
        "orderDir": order_dir or None,
        "limit": limit,
        "offset": offset,
    }
    if assignee:
        filters["assignee"] = assignee
    if due_date_from != -1:
        filters["dueDateFrom"] = due_date_from
    if due_date_to != -1:
        filters["dueDateTo"] = due_date_to
    if created_at_from != -1:
        filters["createdAtFrom"] = created_at_from
    if created_at_to != -1:
        filters["createdAtTo"] = created_at_to
    if completed_at_from != -1:
        filters["completedAtFrom"] = completed_at_from
    if completed_at_to != -1:
        filters["completedAtTo"] = completed_at_to
    if is_ai_suggested != -1:
        filters["isAiSuggested"] = is_ai_suggested

    result = await execute_on_client(action="select", table="tasks", filters=filters)
    rows = result.get("rows", [])
    if not rows:
        return "No tasks found matching the given filters."
    lines = [
        f"- {r['title']} (status: {r['status']}, priority: {r['priority']}, "
        f"dueDate: {r.get('dueDate')}, completedAt: {r.get('completedAt')}, id: {r['id']})"
        for r in rows
    ]
    return f"Found {len(rows)} task(s):\n" + "\n".join(lines)


@tool
async def count_tasks(
    project_id: str = "",
    status: str = "",
    priority: str = "",
    assignee: str = "",
    search: str = "",
    due_date_from: int = -1,
    due_date_to: int = -1,
    created_at_from: int = -1,
    created_at_to: int = -1,
    completed_at_from: int = -1,
    completed_at_to: int = -1,
    is_ai_suggested: int = -1,
) -> str:
    """Count tasks matching the given filters without returning rows.

    Use this instead of list_tasks for "how many" questions — it is much cheaper.
    Same filter parameters as list_tasks (no limit/offset/order_by needed).

    due_date_from / due_date_to: ms epoch range for dueDate. Use -1 to omit.
    created_at_from / created_at_to: ms epoch range for createdAt. Use -1 to omit.
    completed_at_from / completed_at_to: ms epoch range for completedAt. Use -1 to omit.
    Tip — for natural-language windows take due_date_from / due_date_to from the DATE CONTEXT block;
    do not compute boundaries from the current UTC instant.
    """
    normalized_project_id = project_id if (project_id and _is_uuid(project_id)) else ""
    filters: dict[str, Any] = {
        "projectId": normalized_project_id or None,
        "status": status or None,
        "priority": priority or None,
        "search": search or None,
    }
    if assignee:
        filters["assignee"] = assignee
    if due_date_from != -1:
        filters["dueDateFrom"] = due_date_from
    if due_date_to != -1:
        filters["dueDateTo"] = due_date_to
    if created_at_from != -1:
        filters["createdAtFrom"] = created_at_from
    if created_at_to != -1:
        filters["createdAtTo"] = created_at_to
    if completed_at_from != -1:
        filters["completedAtFrom"] = completed_at_from
    if completed_at_to != -1:
        filters["completedAtTo"] = completed_at_to
    if is_ai_suggested != -1:
        filters["isAiSuggested"] = is_ai_suggested

    result = await execute_on_client(action="count", table="tasks", filters=filters)
    return f"Task count: {result.get('count', 0)}"


@tool
async def create_task(
    title: str,
    description: str = "",
    status: str = "todo",
    priority: str = "medium",
    assignees: str = "[]",
    due_date: int = 0,
    project_id: str = "",
    is_ai_suggested: int = 0,
) -> str:
    """Create a new task.
    title: task title (required)
    description: optional details
    status: todo | in_progress | done  (default: todo)
    priority: high | medium | low  (default: medium)
    assignees: JSON-encoded array of assignee names, e.g. '["Alice"]'
    due_date: Unix timestamp in milliseconds; 0 means no due date
    project_id: optional UUID of the parent project
    is_ai_suggested: 1 if proactively suggested, 0 if user-requested

    completedAt is set automatically when status is 'done'.
    """
    result = await execute_on_client(
        action="insert",
        table="tasks",
        data={
            "title": title,
            "description": description or None,
            "status": status,
            "priority": priority,
            "assignee": assignees,
            "dueDate": due_date or None,
            "projectId": project_id or None,
            "isAiSuggested": is_ai_suggested,
        },
    )
    row = result["row"]
    return (
        f"Task created: '{row['title']}' "
        f"(id: {row['id']}, status: {row['status']}, priority: {row['priority']})"
    )


@tool
async def update_task(
    task_id: str,
    title: str = "",
    description: str = "",
    status: str = "",
    priority: str = "",
    assignees: str = "",
    due_date: int = -1,
    project_id: str = "",
) -> str:
    """Update fields on an existing task. Only pass fields you want to change.
    task_id: the task's UUID (required)
    due_date: -1 means unchanged; 0 clears the due date; any positive value sets it

    completedAt is managed automatically:
      - setting status to 'done' records the current timestamp
      - changing status away from 'done' clears completedAt
    """
    updates: dict[str, Any] = {}
    if title:
        updates["title"] = title
    if description:
        updates["description"] = description
    if status:
        updates["status"] = status
    if priority:
        updates["priority"] = priority
    if assignees:
        updates["assignee"] = assignees
    if due_date != -1:
        updates["dueDate"] = due_date or None
    if project_id:
        updates["projectId"] = project_id
    result = await execute_on_client(
        action="update",
        table="tasks",
        data={"id": task_id, "updates": updates},
    )
    row = result["row"]
    return f"Task updated: '{row['title']}' (id: {row['id']}, status: {row['status']})"


@tool
async def delete_task(task_id: str) -> str:
    """Delete a task permanently by its UUID."""
    await execute_on_client(action="delete", table="tasks", data={"id": task_id})
    return f"Task {task_id} deleted."


@tool
async def list_tasks_due_today(user_timezone: str = "UTC", include_done: bool = False) -> str:
    """List all tasks whose due date falls on today's date.

    user_timezone: IANA timezone name (e.g. 'Europe/Rome', 'America/New_York').
    Always pass the user's timezone so 'today' is computed in their local time.
    include_done: set True to also include already-completed tasks due today (default False).
    """
    try:
        from zoneinfo import ZoneInfo
        tz = ZoneInfo(user_timezone or "UTC")
    except Exception:
        tz = timezone.utc
    now_local = datetime.now(tz=tz)
    start_dt = datetime(now_local.year, now_local.month, now_local.day, tzinfo=tz)
    start_ms = int(start_dt.timestamp() * 1000)
    end_ms = start_ms + 86_400_000 - 1
    filters: dict[str, Any] = {"dueDateFrom": start_ms, "dueDateTo": end_ms}
    if not include_done:
        filters["status"] = "todo"
    result = await execute_on_client(
        action="select",
        table="tasks",
        filters=filters,
    )
    rows = result.get("rows", [])
    if not rows:
        return "No tasks are due today."
    lines = [
        f"- {r['title']} (priority: {r['priority']}, status: {r['status']}, id: {r['id']})"
        for r in rows
    ]
    return f"Tasks due today ({len(rows)}):\n" + "\n".join(lines)


# ── Task comment tools ────────────────────────────────────────────────


@tool
async def list_task_comments(task_id: str) -> str:
    """List all comments on a task by its UUID."""
    result = await execute_on_client(
        action="select",
        table="taskComments",
        filters={"taskId": task_id},
    )
    rows = result.get("rows", [])
    if not rows:
        return f"No comments found for task {task_id}."
    lines = [f"- [{r['author']}]: {r['content']} (id: {r['id']})" for r in rows]
    return f"Found {len(rows)} comment(s):\n" + "\n".join(lines)


@tool
async def add_task_comment(task_id: str, author: str, content: str) -> str:
    """Add a comment to a task.
    task_id: UUID of the task to comment on
    author: name or ID of the comment author
    content: comment text
    """
    result = await execute_on_client(
        action="insert",
        table="taskComments",
        data={"taskId": task_id, "author": author, "content": content},
    )
    row = result.get("row", {})
    row_author = row.get("author", author)
    row_task_id = row.get("taskId") or row.get("task_id") or task_id
    row_comment_id = row.get("id", "unknown")
    return f"Comment added by {row_author} on task {row_task_id} (comment id: {row_comment_id})."


@tool
async def delete_task_comment(comment_id: str) -> str:
    """Delete a task comment by its UUID."""
    await execute_on_client(action="delete", table="taskComments", data={"id": comment_id})
    return f"Comment {comment_id} deleted."


# ── Agent ─────────────────────────────────────────────────────────────


TASK_TOOLS: list[Any] = [
    list_tasks,
    count_tasks,
    create_task,
    update_task,
    delete_task,
    list_tasks_due_today,
    list_task_comments,
    add_task_comment,
    delete_task_comment,
]

TASK_READ_TOOLS: list[Any] = [
    list_tasks,
    count_tasks,
    list_tasks_due_today,
    list_task_comments,
]