use module_big_fish::{BigFishAnchorPack, BigFishCreationStage};
use platform_llm::{LlmClient, LlmMessage, LlmStreamDelta, LlmTextRequest};
use serde::{Deserialize, Serialize};
use serde_json::{Value as JsonValue, json};
use spacetime_client::{
    BigFishAgentMessageRecord, BigFishMessageFinalizeRecordInput, BigFishSessionRecord,
};

use crate::creation_agent_anchor_templates::{
    get_creation_agent_anchor_template, render_anchor_question_block,
};

#[derive(Clone, Debug)]
pub(crate) struct BigFishAgentTurnRequest<'a> {
    pub llm_client: Option<&'a LlmClient>,
    pub session: &'a BigFishSessionRecord,
}

#[derive(Clone, Debug)]
pub(crate) struct BigFishAgentTurnResult {
    pub assistant_reply_text: String,
    pub stage: String,
    pub progress_percent: u32,
    pub anchor_pack_json: String,
    pub error_message: Option<String>,
}

#[derive(Clone, Debug)]
pub(crate) struct BigFishAgentTurnError {
    message: String,
}

impl BigFishAgentTurnError {
    fn new(message: impl Into<String>) -> Self {
        Self {
            message: message.into(),
        }
    }
}

impl std::fmt::Display for BigFishAgentTurnError {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        formatter.write_str(&self.message)
    }
}

impl std::error::Error for BigFishAgentTurnError {}

#[derive(Clone, Debug, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
struct BigFishAgentModelOutput {
    reply_text: String,
    progress_percent: u32,
    next_anchor_pack: BigFishAnchorPack,
}

const BIG_FISH_AGENT_SYSTEM_PROMPT: &str = r#"你是一个负责和创作者共创“大鱼吃小鱼”竖屏玩法的中文创意策划。

你必须把用户灵感收束成可以编译为可玩草稿的玩法、生态视觉、成长阶梯和风险节奏。

你必须同时输出：
1. 一段直接发给用户的中文回复 replyText
2. 当前进度 progressPercent
3. 下一轮完整可用的 nextAnchorPack

硬约束：
1. 只能输出 JSON，不能输出代码块或解释
2. nextAnchorPack 必须是完整对象，不能只输出 patch
3. replyText 必须是自然中文，不能提“字段”“锚点”“结构”“JSON”等内部词
4. replyText 一次最多推进一个最关键问题
5. 必须对齐 RPG 共创的体验：先理解玩家幻想，再收束成能进入运行时的可玩效果
6. progressPercent 范围只能是 0 到 100
7. status 只能使用 missing / inferred / confirmed / locked
"#;

const BIG_FISH_AGENT_OUTPUT_CONTRACT: &str = r#"请严格按以下 JSON 输出，不要输出其他文字：
{
  "replyText": "",
  "progressPercent": 0,
  "nextAnchorPack": {
    "gameplayPromise": {
      "key": "gameplayPromise",
      "label": "玩法承诺",
      "value": "",
      "status": "missing"
    },
    "ecologyVisualTheme": {
      "key": "ecologyVisualTheme",
      "label": "生态视觉主题",
      "value": "",
      "status": "missing"
    },
    "growthLadder": {
      "key": "growthLadder",
      "label": "成长阶梯",
      "value": "",
      "status": "missing"
    },
    "riskTempo": {
      "key": "riskTempo",
      "label": "风险节奏",
      "value": "",
      "status": "missing"
    }
  }
}"#;

pub(crate) async fn run_big_fish_agent_turn<F>(
    request: BigFishAgentTurnRequest<'_>,
    mut on_reply_update: F,
) -> Result<BigFishAgentTurnResult, BigFishAgentTurnError>
where
    F: FnMut(&str),
{
    let llm_client = request
        .llm_client
        .ok_or_else(|| BigFishAgentTurnError::new("当前模型不可用，请稍后重试。"))?;
    let prompt = build_big_fish_agent_prompt(request.session);
    let mut latest_reply_text = String::new();
    let response = llm_client
        .stream_text(
            LlmTextRequest::new(vec![
                LlmMessage::system(format!("{BIG_FISH_AGENT_SYSTEM_PROMPT}\n\n{prompt}")),
                LlmMessage::user("请按约定输出这一轮的 JSON。"),
            ]),
            |delta: &LlmStreamDelta| {
                if let Some(reply_progress) =
                    extract_reply_text_from_partial_json(delta.accumulated_text.as_str())
                    && reply_progress != latest_reply_text
                {
                    latest_reply_text = reply_progress.clone();
                    on_reply_update(reply_progress.as_str());
                }
            },
        )
        .await
        .map_err(|_| BigFishAgentTurnError::new("大鱼吃小鱼聊天生成失败，请稍后重试。"))?;

    let parsed = parse_json_response_text(response.content.as_str())
        .map_err(|_| BigFishAgentTurnError::new("大鱼吃小鱼聊天结果解析失败，请稍后重试。"))?;
    let output = parse_big_fish_model_output(&parsed)?;
    if output.reply_text != latest_reply_text {
        on_reply_update(output.reply_text.as_str());
    }

    Ok(BigFishAgentTurnResult {
        assistant_reply_text: output.reply_text,
        stage: BigFishCreationStage::CollectingAnchors.as_str().to_string(),
        progress_percent: output.progress_percent.min(100),
        anchor_pack_json: serde_json::to_string(&output.next_anchor_pack)
            .unwrap_or_else(|_| "{}".to_string()),
        error_message: None,
    })
}

pub(crate) fn build_finalize_record_input(
    session_id: String,
    owner_user_id: String,
    assistant_message_id: String,
    result: BigFishAgentTurnResult,
    updated_at_micros: i64,
) -> BigFishMessageFinalizeRecordInput {
    BigFishMessageFinalizeRecordInput {
        session_id,
        owner_user_id,
        assistant_message_id: Some(assistant_message_id),
        assistant_reply_text: Some(result.assistant_reply_text),
        stage: result.stage,
        progress_percent: result.progress_percent,
        anchor_pack_json: result.anchor_pack_json,
        error_message: result.error_message,
        updated_at_micros,
    }
}

pub(crate) fn build_failed_finalize_record_input(
    session_id: String,
    owner_user_id: String,
    session: &BigFishSessionRecord,
    error_message: String,
    updated_at_micros: i64,
) -> BigFishMessageFinalizeRecordInput {
    BigFishMessageFinalizeRecordInput {
        session_id,
        owner_user_id,
        assistant_message_id: None,
        assistant_reply_text: None,
        stage: session.stage.clone(),
        progress_percent: session.progress_percent,
        anchor_pack_json: serialize_record_anchor_pack(&session.anchor_pack),
        error_message: Some(error_message),
        updated_at_micros,
    }
}

fn build_big_fish_agent_prompt(session: &BigFishSessionRecord) -> String {
    let anchor_question_block = get_creation_agent_anchor_template("big_fish")
        .map(render_anchor_question_block)
        .unwrap_or_else(|| "模板目标：收束成可玩的竖屏大鱼吃小鱼玩法草稿。".to_string());
    format!(
        "{anchor_question_block}\n\n当前是第 {turn} 轮，当前进度 {progress}% 。\n\n当前 anchor pack：\n{anchor_pack}\n\n最近聊天记录：\n{chat_history}\n\n{contract}",
        anchor_question_block = anchor_question_block,
        turn = session.current_turn.saturating_add(1),
        progress = session.progress_percent,
        anchor_pack = serialize_record_anchor_pack(&session.anchor_pack),
        chat_history =
            serde_json::to_string_pretty(&build_chat_history(session.messages.as_slice()))
                .unwrap_or_else(|_| "[]".to_string()),
        contract = BIG_FISH_AGENT_OUTPUT_CONTRACT,
    )
}

fn build_chat_history(messages: &[BigFishAgentMessageRecord]) -> Vec<JsonValue> {
    messages
        .iter()
        .map(|message| {
            json!({
                "role": message.role,
                "kind": message.kind,
                "content": message.text,
            })
        })
        .collect()
}

fn parse_big_fish_model_output(
    parsed: &JsonValue,
) -> Result<BigFishAgentModelOutput, BigFishAgentTurnError> {
    serde_json::from_value::<BigFishAgentModelOutput>(parsed.clone())
        .map_err(|_| BigFishAgentTurnError::new("大鱼吃小鱼模型结果缺少必要内容，请稍后重试。"))
}

fn serialize_record_anchor_pack(anchor_pack: &spacetime_client::BigFishAnchorPackRecord) -> String {
    serde_json::to_string_pretty(&json!({
        "gameplayPromise": {
            "key": anchor_pack.gameplay_promise.key,
            "label": anchor_pack.gameplay_promise.label,
            "value": anchor_pack.gameplay_promise.value,
            "status": anchor_pack.gameplay_promise.status,
        },
        "ecologyVisualTheme": {
            "key": anchor_pack.ecology_visual_theme.key,
            "label": anchor_pack.ecology_visual_theme.label,
            "value": anchor_pack.ecology_visual_theme.value,
            "status": anchor_pack.ecology_visual_theme.status,
        },
        "growthLadder": {
            "key": anchor_pack.growth_ladder.key,
            "label": anchor_pack.growth_ladder.label,
            "value": anchor_pack.growth_ladder.value,
            "status": anchor_pack.growth_ladder.status,
        },
        "riskTempo": {
            "key": anchor_pack.risk_tempo.key,
            "label": anchor_pack.risk_tempo.label,
            "value": anchor_pack.risk_tempo.value,
            "status": anchor_pack.risk_tempo.status,
        },
    }))
    .unwrap_or_else(|_| "{}".to_string())
}

fn parse_json_response_text(text: &str) -> Result<JsonValue, serde_json::Error> {
    if let Ok(value) = serde_json::from_str::<JsonValue>(text) {
        return Ok(value);
    }
    let Some(start) = text.find('{') else {
        return serde_json::from_str(text);
    };
    let Some(end) = text.rfind('}') else {
        return serde_json::from_str(text);
    };
    serde_json::from_str(&text[start..=end])
}

fn extract_reply_text_from_partial_json(text: &str) -> Option<String> {
    let marker = "\"replyText\"";
    let marker_index = text.find(marker)?;
    let after_marker = &text[marker_index + marker.len()..];
    let colon_index = after_marker.find(':')?;
    let after_colon = after_marker[colon_index + 1..].trim_start();
    let content = after_colon.strip_prefix('"')?;
    let mut result = String::new();
    let mut escaped = false;
    for character in content.chars() {
        if escaped {
            result.push(match character {
                'n' => '\n',
                'r' => '\r',
                't' => '\t',
                '"' => '"',
                '\\' => '\\',
                other => other,
            });
            escaped = false;
            continue;
        }
        if character == '\\' {
            escaped = true;
            continue;
        }
        if character == '"' {
            return Some(result);
        }
        result.push(character);
    }
    if result.is_empty() {
        None
    } else {
        Some(result)
    }
}