use shared_kernel::normalize_required_string;

use crate::{
    EDITOR_AGENT_MAX_ATTACHMENTS, EditorAgentConversationCreateInput,
    EditorAgentConversationDeleteInput, EditorAgentConversationTouchInput, EditorAgentError,
};

pub fn validate_conversation_key(
    conversation_id: &str,
    owner_user_id: &str,
) -> Result<(String, String), EditorAgentError> {
    let conversation_id = normalize_required_string(conversation_id)
        .ok_or(EditorAgentError::MissingConversationId)?;
    let owner_user_id =
        normalize_required_string(owner_user_id).ok_or(EditorAgentError::MissingOwnerUserId)?;
    Ok((conversation_id, owner_user_id))
}

pub fn validate_create_conversation(
    input: &EditorAgentConversationCreateInput,
) -> Result<(), EditorAgentError> {
    validate_conversation_key(&input.conversation_id, &input.owner_user_id)?;
    if normalize_required_string(&input.project_id).is_none() {
        return Err(EditorAgentError::MissingProjectId);
    }
    Ok(())
}

pub fn validate_touch_conversation(
    input: &EditorAgentConversationTouchInput,
) -> Result<(), EditorAgentError> {
    validate_conversation_key(&input.conversation_id, &input.owner_user_id)?;
    Ok(())
}

pub fn validate_delete_conversation(
    input: &EditorAgentConversationDeleteInput,
) -> Result<(), EditorAgentError> {
    validate_conversation_key(&input.conversation_id, &input.owner_user_id)?;
    Ok(())
}

/// 校验会话访问权：拥有者匹配且未软删。
pub fn ensure_conversation_accessible(
    snapshot_owner_user_id: &str,
    snapshot_deleted: bool,
    requester_user_id: &str,
) -> Result<(), EditorAgentError> {
    if snapshot_owner_user_id != requester_user_id {
        return Err(EditorAgentError::NotConversationOwner);
    }
    if snapshot_deleted {
        return Err(EditorAgentError::ConversationDeleted);
    }
    Ok(())
}

/// 校验用户消息：文本不能为空，附件数量不超过上限，附件引用需带资源标识。
pub fn validate_user_message(
    text: &str,
    attachment_reference_ids: &[String],
) -> Result<(), EditorAgentError> {
    if normalize_required_string(text).is_none() {
        return Err(EditorAgentError::EmptyMessage);
    }
    if attachment_reference_ids.len() > EDITOR_AGENT_MAX_ATTACHMENTS {
        return Err(EditorAgentError::TooManyAttachments);
    }
    if attachment_reference_ids
        .iter()
        .any(|reference_id| normalize_required_string(reference_id).is_none())
    {
        return Err(EditorAgentError::InvalidAttachmentReference);
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::derive_conversation_title;

    #[test]
    fn derive_title_truncates_and_normalizes_whitespace() {
        assert_eq!(
            derive_conversation_title("  帮我生成\n一张森林背景  "),
            "帮我生成 一张森林背景"
        );
        assert_eq!(derive_conversation_title(""), "新对话");
        assert_eq!(derive_conversation_title("   \n  "), "新对话");
        let long_text = "一二三四五六七八九十一二三四五六七八九十超出部分";
        assert_eq!(derive_conversation_title(long_text).chars().count(), 20);
    }

    #[test]
    fn validate_user_message_rules() {
        assert_eq!(
            validate_user_message("", &[]),
            Err(EditorAgentError::EmptyMessage)
        );
        assert_eq!(
            validate_user_message("", &["resource-1".to_string()]),
            Err(EditorAgentError::EmptyMessage)
        );
        assert!(validate_user_message("画一棵树", &[]).is_ok());
        let too_many: Vec<String> = (0..10).map(|i| format!("resource-{i}")).collect();
        assert_eq!(
            validate_user_message("画一棵树", &too_many),
            Err(EditorAgentError::TooManyAttachments)
        );
        assert_eq!(
            validate_user_message("画一棵树", &["  ".to_string()]),
            Err(EditorAgentError::InvalidAttachmentReference)
        );
    }

    #[test]
    fn ensure_conversation_accessible_rules() {
        assert!(ensure_conversation_accessible("user-1", false, "user-1").is_ok());
        assert_eq!(
            ensure_conversation_accessible("user-1", false, "user-2"),
            Err(EditorAgentError::NotConversationOwner)
        );
        assert_eq!(
            ensure_conversation_accessible("user-1", true, "user-1"),
            Err(EditorAgentError::ConversationDeleted)
        );
    }
}