//! The AI assistants panel (hub spec §13.4, #97) shared by the
//! administration, organisation and repository settings pages: the
//! level's own assistants, the ones it inherits, and its prompt.

use crate::assistants::{self, Assistant, Available, Fields, APIS, DEFAULT_BUDGET};
use crate::auth::Viewer;
use crate::db::accounts;
use crate::levels::At;
use crate::Shared;
use serde::Deserialize;

#[derive(Deserialize)]
pub struct AssistantForm {
    #[serde(rename = "_csrf")]
    pub csrf_token: String,
    #[serde(default)]
    action: String,
    #[serde(default)]
    id: Option<i64>,
    #[serde(default)]
    name: String,
    #[serde(default)]
    endpoint: String,
    #[serde(default)]
    api: String,
    #[serde(default)]
    model: String,
    #[serde(default)]
    headers: String,
    #[serde(default)]
    token: String,
    #[serde(default)]
    enabled: Option<String>,
    #[serde(default)]
    budget: String,
    #[serde(default)]
    prompt: String,
    /// A provider from the add form's list (#109), filling what is left empty.
    #[serde(default)]
    preset: String,
}

/// Everything the panel shows.
pub struct Panel {
    /// The level's own assistants, each with whether a level above turned
    /// its name off.
    pub own: Vec<Available>,
    /// The ones the levels above provide, outermost first.
    pub inherited: Vec<Available>,
    pub prompt: String,
    /// (where from, text) for each level above that set a prompt.
    pub inherited_prompts: Vec<(String, String)>,
    pub apis: Vec<&'static str>,
    pub default_budget: i64,
    pub presets: Vec<(&'static str, &'static str, &'static str, &'static str, &'static str)>,
}

pub async fn panel(app: &Shared, at: &At) -> sqlx::Result<Panel> {
    let (own, inherited): (Vec<_>, Vec<_>) =
        assistants::available(&app.db, at.scope, &at.owner).await?.into_iter().partition(|a| a.from.is_empty());
    Ok(Panel {
        own,
        inherited,
        prompt: assistants::prompt(&app.db, at.scope).await?,
        inherited_prompts: assistants::inherited_prompts(&app.db, at.scope, &at.owner).await?,
        apis: APIS.to_vec(),
        default_budget: DEFAULT_BUDGET,
        presets: assistants::PRESETS.to_vec(),
    })
}

fn name_ok(name: &str) -> bool {
    !name.is_empty() && name.chars().count() <= 40 && name.chars().all(|c| c.is_alphanumeric() || matches!(c, ' ' | '.' | '-' | '_'))
}

fn endpoint_ok(url: &str) -> bool {
    (url.starts_with("http://") || url.starts_with("https://")) && url.len() <= 2000 && !url.contains(char::is_whitespace)
}

impl AssistantForm {
    fn clone_shallow(&self) -> AssistantForm {
        AssistantForm {
            csrf_token: String::new(),
            action: self.action.clone(),
            id: self.id,
            name: self.name.clone(),
            endpoint: self.endpoint.clone(),
            api: self.api.clone(),
            model: self.model.clone(),
            headers: self.headers.clone(),
            token: String::new(),
            enabled: self.enabled.clone(),
            budget: self.budget.clone(),
            prompt: String::new(),
            preset: self.preset.clone(),
        }
    }
}

/// When the endpoint lists its models, the model must be one of them
/// (#109); `Err` names a few it does offer.
async fn model_offered(fields: &Fields, token: &str) -> Result<(), String> {
    match assistants::list_models(&fields.endpoint, &fields.api, token).await {
        Ok(models) if !models.iter().any(|m| m == &fields.model) => {
            let close: Vec<&String> = {
                let stem = fields.model.split(['-', '.']).next().unwrap_or("").to_lowercase();
                let near: Vec<&String> = models.iter().filter(|m| m.to_lowercase().contains(&stem)).take(8).collect();
                if near.is_empty() {
                    models.iter().take(8).collect()
                } else {
                    near
                }
            };
            Err(format!(
                "{} is not a model this endpoint offers. It offers, among others: {}. Use List models to pick one.",
                fields.model,
                close.iter().map(|m| m.as_str()).collect::<Vec<_>>().join(", ")
            ))
        }
        _ => Ok(()),
    }
}

/// The form's details checked: `Err` is the message for the person.
fn fields(f: &AssistantForm) -> Result<Fields, String> {
    let mut f_owned;
    let f = match assistants::PRESETS.iter().find(|p| p.0 == f.preset) {
        Some(&(_, _, name, endpoint, api)) => {
            f_owned = f.clone_shallow();
            if f_owned.name.trim().is_empty() {
                f_owned.name = name.into();
            }
            if f_owned.endpoint.trim().is_empty() {
                f_owned.endpoint = endpoint.into();
            }
            if !APIS.contains(&f_owned.api.as_str()) || f.endpoint.trim().is_empty() {
                f_owned.api = api.into();
            }
            &f_owned
        }
        None => f,
    };
    let name = f.name.trim().to_string();
    if !name_ok(&name) {
        return Err("An assistant's name is up to 40 letters, digits, spaces, dots, dashes or underscores.".into());
    }
    let endpoint = f.endpoint.trim().to_string();
    if !endpoint_ok(&endpoint) {
        return Err("The endpoint is the full URL the request is posted to, starting with https://.".into());
    }
    if !APIS.contains(&f.api.as_str()) {
        return Err("The API is chat-completions or anthropic-messages.".into());
    }
    let model = f.model.trim().to_string();
    if model.is_empty() || model.len() > 100 || model.contains(char::is_whitespace) {
        return Err("A model name is needed, such as claude-opus-5-5 or gpt-5.".into());
    }
    let headers = f.headers.trim().to_string();
    if let Err(line) = assistants::parse_headers(&headers) {
        return Err(format!("Extra headers are one Name: value per line; this line is not: {line}"));
    }
    if headers.lines().count() > 10 {
        return Err("Up to ten extra headers.".into());
    }
    let budget = if f.budget.trim().is_empty() {
        DEFAULT_BUDGET
    } else {
        match f.budget.trim().parse::<i64>() {
            Ok(n) if (1_000..=2_000_000).contains(&n) => n,
            _ => return Err("The context budget is a number of characters from 1000 to 2000000.".into()),
        }
    };
    Ok(Fields { name, endpoint, api: f.api.clone(), model, headers, enabled: f.enabled.is_some(), budget })
}

/// Apply the panel's form: `Ok(notice)` or `Err(message for the user)`.
pub async fn apply(app: &Shared, viewer: &Viewer, at: &At, f: AssistantForm) -> sqlx::Result<Result<String, String>> {
    let owned = |a: Option<Assistant>| a.filter(|a| a.scope() == at.scope);
    let actor = viewer.account();
    Ok(Ok(match (f.action.as_str(), f.id) {
        ("add", None) => {
            let fields = match fields(&f) {
                Ok(x) => x,
                Err(e) => return Ok(Err(e)),
            };
            if let Err(e) = model_offered(&fields, f.token.trim()).await {
                return Ok(Err(e));
            }
            let token = app.assistant_key.seal(f.token.trim());
            match assistants::create(&app.db, at.scope, &fields, &token).await? {
                Some(a) => {
                    accounts::audit(&app.db, actor, "assistant.added", &at.label, &a.name).await.ok();
                    // Try it at once, so a wrong endpoint or token shows here.
                    match assistants::test(app, &a).await {
                        Ok(answer) => format!("{} added and answered: {answer}", a.name),
                        Err(why) => {
                            format!("{} added, but did not answer: {why}. Check the endpoint, API and token, then TEST CONNECTION.", a.name)
                        }
                    }
                }
                None => return Ok(Err(format!("There is already an assistant called {} here.", fields.name))),
            }
        }
        ("update", Some(id)) => {
            let Some(a) = owned(assistants::get(&app.db, id).await?) else { return Ok(Err("No such assistant.".into())) };
            let fields = match fields(&f) {
                Ok(x) => x,
                Err(e) => return Ok(Err(e)),
            };
            let token = f.token.trim();
            let stored = if token.is_empty() { app.assistant_key.open(&a.token).unwrap_or_default() } else { token.to_string() };
            if let Err(e) = model_offered(&fields, &stored).await {
                return Ok(Err(e));
            }
            let sealed = (!token.is_empty()).then(|| app.assistant_key.seal(token));
            if !assistants::update(&app.db, id, &fields, sealed.as_deref()).await? {
                return Ok(Err(format!("There is already an assistant called {} here.", fields.name)));
            }
            if a.name != fields.name {
                assistants::rename_in_history(&app.db, at.scope, &at.owner, &a.name, &fields.name).await?;
            }
            accounts::audit(&app.db, actor, "assistant.updated", &at.label, &a.name).await.ok();
            format!("{} updated.", fields.name)
        }
        ("toggle", Some(id)) => {
            let Some(a) = owned(assistants::get(&app.db, id).await?) else { return Ok(Err("No such assistant.".into())) };
            assistants::set_enabled(&app.db, id, !a.enabled).await?;
            accounts::audit(&app.db, actor, if a.enabled { "assistant.disabled" } else { "assistant.enabled" }, &at.label, &a.name)
                .await
                .ok();
            format!("{} is {}.", a.name, if a.enabled { "off" } else { "on" })
        }
        ("delete", Some(id)) => {
            let Some(a) = owned(assistants::get(&app.db, id).await?) else { return Ok(Err("No such assistant.".into())) };
            assistants::delete(&app.db, id).await?;
            accounts::audit(&app.db, actor, "assistant.deleted", &at.label, &a.name).await.ok();
            format!("{} deleted.", a.name)
        }
        ("test", Some(id)) => {
            let Some(a) = owned(assistants::get(&app.db, id).await?) else { return Ok(Err("No such assistant.".into())) };
            match assistants::test(app, &a).await {
                Ok(answer) => format!("{} answered: {answer}", a.name),
                Err(why) => return Ok(Err(format!("{} did not answer: {why}. Check the endpoint, API and token.", a.name))),
            }
        }
        ("prompt", _) => {
            if f.prompt.chars().count() > 20_000 {
                return Ok(Err("A prompt is up to 20000 characters.".into()));
            }
            assistants::set_prompt(&app.db, at.scope, &f.prompt).await?;
            accounts::audit(&app.db, actor, "assistant.prompt", &at.label, "").await.ok();
            if f.prompt.trim().is_empty() {
                "Prompt cleared.".to_string()
            } else {
                "Prompt saved.".to_string()
            }
        }
        _ => return Ok(Err("Unknown action.".into())),
    }))
}

#[derive(Deserialize)]
pub struct ModelsForm {
    #[serde(rename = "_csrf")]
    pub csrf_token: String,
    #[serde(default)]
    id: Option<i64>,
    #[serde(default)]
    endpoint: String,
    #[serde(default)]
    api: String,
    #[serde(default)]
    token: String,
    #[serde(default)]
    preset: String,
}

/// The models a provider offers, as JSON for the form's List models
/// button (#109): `{"models": [...]}` or `{"error": "..."}`. With `id`,
/// the stored token of that assistant at this level is used when none is
/// typed.
pub async fn models(app: &Shared, at: &At, f: ModelsForm) -> sqlx::Result<serde_json::Value> {
    let preset = assistants::PRESETS.iter().find(|p| p.0 == f.preset);
    let endpoint =
        if f.endpoint.trim().is_empty() { preset.map(|p| p.3.to_string()).unwrap_or_default() } else { f.endpoint.trim().to_string() };
    let api = if APIS.contains(&f.api.as_str()) {
        f.api.clone()
    } else {
        preset.map(|p| p.4.to_string()).unwrap_or_else(|| "chat-completions".into())
    };
    let mut token = f.token.trim().to_string();
    if token.is_empty() {
        if let Some(id) = f.id {
            if let Some(a) = assistants::get(&app.db, id).await?.filter(|a| a.scope() == at.scope) {
                token = app.assistant_key.open(&a.token).unwrap_or_default();
            }
        }
    }
    Ok(match assistants::list_models(&endpoint, &api, &token).await {
        Ok(m) => serde_json::json!({ "models": m }),
        Err(e) => serde_json::json!({ "error": e }),
    })
}