use serde_json::{Map, Value, json};

use crate::{
    AudioError, BackgroundMusicTaskRequest, EditorBackgroundMusicTaskRequest, SUNO_DEFAULT_MODEL,
    SUNO_PROMPT_MAX_CHARS, SUNO_TAGS_MAX_CHARS, SUNO_TITLE_MAX_CHARS,
};

pub fn build_background_music_task_body(
    request: BackgroundMusicTaskRequest,
) -> Result<Value, AudioError> {
    let prompt =
        normalize_limited_text_allow_empty(&request.prompt, "prompt", SUNO_PROMPT_MAX_CHARS)?;
    let title = normalize_limited_text(&request.title, "title", SUNO_TITLE_MAX_CHARS)?;
    let tags = request
        .tags
        .as_deref()
        .map(|value| normalize_limited_text(value, "tags", SUNO_TAGS_MAX_CHARS))
        .transpose()?;
    let model = normalize_optional_text(request.model.as_deref())
        .unwrap_or_else(|| SUNO_DEFAULT_MODEL.to_string());

    let mut body = Map::from_iter([
        ("prompt".to_string(), Value::String(prompt)),
        ("mv".to_string(), Value::String(model)),
        ("title".to_string(), Value::String(title)),
        ("task".to_string(), Value::String("generate".to_string())),
        (
            "make_instrumental".to_string(),
            Value::Bool(request.instrumental),
        ),
    ]);
    if let Some(tags) = tags {
        body.insert("tags".to_string(), Value::String(tags));
    }
    Ok(Value::Object(body))
}

pub fn build_editor_background_music_task_body(
    request: EditorBackgroundMusicTaskRequest,
) -> Result<Value, AudioError> {
    let prompt =
        crate::validate_background_music_generation_prompt(&request.gpt_description_prompt)?;
    let model = normalize_optional_text(request.model.as_deref())
        .unwrap_or_else(|| SUNO_DEFAULT_MODEL.to_string());
    Ok(json!({
        "mv": model,
        "gpt_description_prompt": prompt.prompt,
        "make_instrumental": request.make_instrumental,
    }))
}

pub fn normalize_limited_text(
    value: &str,
    field: &'static str,
    max_chars: usize,
) -> Result<String, AudioError> {
    let normalized = value.trim().to_string();
    if normalized.is_empty() {
        return Err(AudioError::invalid_request(format!("{field} 不能为空")));
    }
    if normalized.chars().count() > max_chars {
        return Err(AudioError::invalid_request(format!(
            "{field} 超过 {} 字符",
            max_chars
        )));
    }
    Ok(normalized)
}

pub fn normalize_limited_text_allow_empty(
    value: &str,
    field: &'static str,
    max_chars: usize,
) -> Result<String, AudioError> {
    let normalized = value.trim().to_string();
    if normalized.chars().count() > max_chars {
        return Err(AudioError::invalid_request(format!(
            "{field} 超过 {} 字符",
            max_chars
        )));
    }
    Ok(normalized)
}

pub fn normalize_optional_text(value: Option<&str>) -> Option<String> {
    value
        .map(str::trim)
        .filter(|value| !value.is_empty())
        .map(ToOwned::to_owned)
}