from enum import Enum
from typing import Dict, List, Optional

from pydantic import BaseModel, Field, field_validator

from letta.constants import DEFAULT_EMBEDDING_CHUNK_SIZE
from letta.schemas.block import CreateBlock
from letta.schemas.embedding_config import EmbeddingConfig
from letta.schemas.letta_base import OrmMetadataBase
from letta.schemas.llm_config import LLMConfig
from letta.schemas.memory import Memory
from letta.schemas.message import Message, MessageCreate
from letta.schemas.openai.chat_completion_response import UsageStatistics
from letta.schemas.source import Source
from letta.schemas.tool import Tool
from letta.schemas.tool_rule import ToolRule
from letta.utils import create_random_username


class AgentType(str, Enum):
    """
    Enum to represent the type of agent.
    """

    memgpt_agent = "memgpt_agent"
    split_thread_agent = "split_thread_agent"
    o1_agent = "o1_agent"
    offline_memory_agent = "offline_memory_agent"
    chat_only_agent = "chat_only_agent"


class AgentState(OrmMetadataBase, validate_assignment=True):
    """
    Representation of an agent's state. This is the state of the agent at a given time, and is persisted in the DB backend. The state has all the information needed to recreate a persisted agent.

    Parameters:
        id (str): The unique identifier of the agent.
        name (str): The name of the agent (must be unique to the user).
        created_at (datetime): The datetime the agent was created.
        message_ids (List[str]): The ids of the messages in the agent's in-context memory.
        memory (Memory): The in-context memory of the agent.
        tools (List[str]): The tools used by the agent. This includes any memory editing functions specified in `memory`.
        system (str): The system prompt used by the agent.
        llm_config (LLMConfig): The LLM configuration used by the agent.
        embedding_config (EmbeddingConfig): The embedding configuration used by the agent.

    """

    __id_prefix__ = "agent"

    # NOTE: this is what is returned to the client and also what is used to initialize `Agent`
    id: str = Field(..., description="The id of the agent. Assigned by the database.")
    name: str = Field(..., description="The name of the agent.")
    # tool rules
    tool_rules: Optional[List[ToolRule]] = Field(default=None, description="The list of tool rules.")

    # in-context memory
    message_ids: Optional[List[str]] = Field(default=None, description="The ids of the messages in the agent's in-context memory.")

    # system prompt
    system: str = Field(..., description="The system prompt used by the agent.")

    # agent configuration
    agent_type: AgentType = Field(..., description="The type of agent.")

    # llm information
    llm_config: LLMConfig = Field(..., description="The LLM configuration used by the agent.")
    embedding_config: EmbeddingConfig = Field(..., description="The embedding configuration used by the agent.")

    # This is an object representing the in-process state of a running `Agent`
    # Field in this object can be theoretically edited by tools, and will be persisted by the ORM
    organization_id: Optional[str] = Field(None, description="The unique identifier of the organization associated with the agent.")

    description: Optional[str] = Field(None, description="The description of the agent.")
    metadata_: Optional[Dict] = Field(None, description="The metadata of the agent.", alias="metadata_")

    memory: Memory = Field(..., description="The in-context memory of the agent.")
    tools: List[Tool] = Field(..., description="The tools used by the agent.")
    sources: List[Source] = Field(..., description="The sources used by the agent.")
    tags: List[str] = Field(..., description="The tags associated with the agent.")


class CreateAgent(BaseModel, validate_assignment=True):  #
    # all optional as server can generate defaults
    name: str = Field(default_factory=lambda: create_random_username(), description="The name of the agent.")

    # memory creation
    memory_blocks: List[CreateBlock] = Field(
        ...,
        description="The blocks to create in the agent's in-context memory.",
    )
    # TODO: This is a legacy field and should be removed ASAP to force `tool_ids` usage
    tools: Optional[List[str]] = Field(None, description="The tools used by the agent.")
    tool_ids: Optional[List[str]] = Field(None, description="The ids of the tools used by the agent.")
    source_ids: Optional[List[str]] = Field(None, description="The ids of the sources used by the agent.")
    block_ids: Optional[List[str]] = Field(None, description="The ids of the blocks used by the agent.")
    tool_rules: Optional[List[ToolRule]] = Field(None, description="The tool rules governing the agent.")
    tags: Optional[List[str]] = Field(None, description="The tags associated with the agent.")
    system: Optional[str] = Field(None, description="The system prompt used by the agent.")
    agent_type: AgentType = Field(default_factory=lambda: AgentType.memgpt_agent, description="The type of agent.")
    llm_config: Optional[LLMConfig] = Field(None, description="The LLM configuration used by the agent.")
    embedding_config: Optional[EmbeddingConfig] = Field(None, description="The embedding configuration used by the agent.")
    # Note: if this is None, then we'll populate with the standard "more human than human" initial message sequence
    # If the client wants to make this empty, then the client can set the arg to an empty list
    initial_message_sequence: Optional[List[MessageCreate]] = Field(
        None, description="The initial set of messages to put in the agent's in-context memory."
    )
    include_base_tools: bool = Field(True, description="The LLM configuration used by the agent.")
    description: Optional[str] = Field(None, description="The description of the agent.")
    metadata_: Optional[Dict] = Field(None, description="The metadata of the agent.", alias="metadata_")
    llm: Optional[str] = Field(
        None,
        description="The LLM configuration handle used by the agent, specified in the format "
        "provider/model-name, as an alternative to specifying llm_config.",
    )
    embedding: Optional[str] = Field(
        None, description="The embedding configuration handle used by the agent, specified in the format provider/model-name."
    )
    context_window_limit: Optional[int] = Field(None, description="The context window limit used by the agent.")
    embedding_chunk_size: Optional[int] = Field(DEFAULT_EMBEDDING_CHUNK_SIZE, description="The embedding chunk size used by the agent.")
    from_template: Optional[str] = Field(None, description="The template id used to configure the agent")
    project_id: Optional[str] = Field(None, description="The project id that the agent will be associated with.")

    @field_validator("name")
    @classmethod
    def validate_name(cls, name: str) -> str:
        """Validate the requested new agent name (prevent bad inputs)"""

        import re

        if not name:
            # don't check if not provided
            return name

        # TODO: this check should also be added to other model (e.g. User.name)
        # Length check
        if not (1 <= len(name) <= 50):
            raise ValueError("Name length must be between 1 and 50 characters.")

        # Regex for allowed characters (alphanumeric, spaces, hyphens, underscores)
        if not re.match("^[A-Za-z0-9 _-]+$", name):
            raise ValueError("Name contains invalid characters.")

        # Further checks can be added here...
        # TODO

        return name

    @field_validator("llm")
    @classmethod
    def validate_llm(cls, llm: Optional[str]) -> Optional[str]:
        if not llm:
            return llm

        provider_name, model_name = llm.split("/", 1)
        if not provider_name or not model_name:
            raise ValueError("The llm config handle should be in the format provider/model-name")

        return llm

    @field_validator("embedding")
    @classmethod
    def validate_embedding(cls, embedding: Optional[str]) -> Optional[str]:
        if not embedding:
            return embedding

        provider_name, model_name = embedding.split("/", 1)
        if not provider_name or not model_name:
            raise ValueError("The embedding config handle should be in the format provider/model-name")

        return embedding


class UpdateAgent(BaseModel):
    name: Optional[str] = Field(None, description="The name of the agent.")
    tool_ids: Optional[List[str]] = Field(None, description="The ids of the tools used by the agent.")
    source_ids: Optional[List[str]] = Field(None, description="The ids of the sources used by the agent.")
    block_ids: Optional[List[str]] = Field(None, description="The ids of the blocks used by the agent.")
    tags: Optional[List[str]] = Field(None, description="The tags associated with the agent.")
    system: Optional[str] = Field(None, description="The system prompt used by the agent.")
    tool_rules: Optional[List[ToolRule]] = Field(None, description="The tool rules governing the agent.")
    llm_config: Optional[LLMConfig] = Field(None, description="The LLM configuration used by the agent.")
    embedding_config: Optional[EmbeddingConfig] = Field(None, description="The embedding configuration used by the agent.")
    message_ids: Optional[List[str]] = Field(None, description="The ids of the messages in the agent's in-context memory.")
    description: Optional[str] = Field(None, description="The description of the agent.")
    metadata_: Optional[Dict] = Field(None, description="The metadata of the agent.", alias="metadata_")

    class Config:
        extra = "ignore"  # Ignores extra fields


class AgentStepResponse(BaseModel):
    messages: List[Message] = Field(..., description="The messages generated during the agent's step.")
    heartbeat_request: bool = Field(..., description="Whether the agent requested a heartbeat (i.e. follow-up execution).")
    function_failed: bool = Field(..., description="Whether the agent step ended because a function call failed.")
    in_context_memory_warning: bool = Field(
        ..., description="Whether the agent step ended because the in-context memory is near its limit."
    )
    usage: UsageStatistics = Field(..., description="Usage statistics of the LLM call during the agent's step.")