//! HTTP handler functions for the CMS REST API.
//!
//! Each handler takes a service trait (via generics or trait objects) and
//! returns domain-level results. These functions are agnostic about the
//! HTTP framework — callers (e.g. hyper/Axum routes) are responsible for
//! mapping `Result` into HTTP responses with appropriate status codes.
//!
//! ## Handlers
//! - `handle_get_settings` — GET /settings → full settings response
//! - `handle_update_settings` — PUT /settings → partial update + full response
//! - `handle_list_memories` — GET /memories → list of memory summaries
//! - `handle_create_memory` — POST /memories → create/update memory response
//!
//! ## Design
//! Handlers are pure Rust functions with no dependency on the HTTP framework.
//! They receive service trait objects (`&S` or `&M`) and return `Result<T>`.
//! The caller (e.g. a hyper `Service`) is responsible for serialising the
//! response and setting HTTP status codes.

use anyhow::{Context, Result};
use tracing::instrument;

use crate::domain::memory::Memory;
use crate::domain::service::{MemoryService, SettingsService};
use crate::domain::settings::Settings;

use super::dto::{MemoryCreateRequest, MemoryResponse, SettingsResponse, SettingsUpdateRequest};

/// Handle `GET /settings`
///
/// Returns the current settings as a `SettingsResponse`.
///
/// Flow: load settings from service → convert to DTO → return.
#[instrument(skip(service))]
pub fn handle_get_settings<S: SettingsService>(service: &S) -> Result<SettingsResponse> {
    tracing::debug!("handling GET /settings");
    let settings = service.load_settings().context("failed to load settings")?;
    Ok(SettingsResponse::from(settings))
}

/// Handle `PUT /settings`
///
/// Applies a partial update from `req` to the current settings, persists
/// the result, and returns the updated `SettingsResponse`.
///
/// Flow: load current settings → apply each optional field → save → return DTO.
///
/// ## Validation
/// - `internet_mode` must be "Off", "ReadOnly", or "Full" (case-sensitive).
#[instrument(skip(service))]
pub fn handle_update_settings<S: SettingsService>(
    service: &S,
    req: SettingsUpdateRequest,
) -> Result<SettingsResponse> {
    tracing::debug!("handling PUT /settings");
    // Load current settings as baseline for partial update
    let mut settings: Settings = service
        .load_settings()
        .context("failed to load current settings for update")?;

    // Apply each optional field from the request (None = skip, Some = overwrite)
    if let Some(val) = req.internet_mode {
        settings.internet_mode = match val.as_str() {
            "Off" => crate::domain::settings::InternetMode::Off,
            "ReadOnly" => crate::domain::settings::InternetMode::ReadOnly,
            "Full" => crate::domain::settings::InternetMode::Full,
            _ => {
                return Err(anyhow::anyhow!(
                    "invalid internet_mode '{}'; expected Off, ReadOnly, or Full",
                    val
                ));
            }
        };
    }
    if let Some(val) = req.provider {
        settings.provider = val;
    }
    if let Some(val) = req.model {
        settings.model = val;
    }
    if let Some(val) = req.api_keys {
        settings.api_keys = val;
    }
    if let Some(val) = req.max_tokens {
        settings.max_tokens = val;
    }
    if let Some(val) = req.temperature {
        settings.temperature = val;
    }
    if let Some(val) = req.review_max_lessons_per_run {
        settings.review_max_lessons_per_run = val;
    }
    if let Some(val) = req.adaptive_review_max_skip {
        settings.adaptive_review_max_skip = val;
    }
    if let Some(val) = req.verify_command {
        settings.verify_command = val;
    }
    if let Some(val) = req.verify_timeout_ms {
        settings.verify_timeout_ms = val;
    }
    if let Some(val) = req.workflow_max_concurrency {
        settings.workflow_max_concurrency = val;
    }
    if let Some(val) = req.review_enabled {
        settings.flags.review_enabled = val;
    }
    if let Some(val) = req.session_archive_enabled {
        settings.flags.session_archive_enabled = val;
    }
    if let Some(val) = req.lsp_auto_provision {
        settings.flags.lsp_auto_provision = val;
    }
    if let Some(val) = req.lsp_languages {
        settings.lsp_languages = val;
    }
    if let Some(val) = req.hive_mind_node_timeout_ms {
        settings.hive_mind_node_timeout_ms = val;
    }

    service
        .save_settings(&settings)
        .context("failed to save updated settings")?;

    Ok(SettingsResponse::from(settings))
}

/// Handle `GET /memories`
///
/// Lists all memory slugs, returning summary responses for each.
/// Full content is not loaded — callers who need full content should
/// use a dedicated endpoint.
///
/// Flow: list slugs from service → map each to minimal MemoryResponse → return.
#[instrument(skip(service))]
pub fn handle_list_memories<M: MemoryService>(service: &M) -> Result<Vec<MemoryResponse>> {
    tracing::debug!("handling GET /memories");
    let slugs = service.list_memories().context("failed to list memories")?;

    // We can't load individual memories without a load_memory method on the
    // service.  For now, list returns summary info; callers who need full
    // content use a separate endpoint.  Return minimal responses keyed by slug.
    let responses: Vec<MemoryResponse> = slugs
        .into_iter()
        .map(|slug| MemoryResponse {
            name: slug.clone(),
            description: String::new(),
            content: String::new(),
            kind: String::new(),
            created_at: 0,
            updated_at: 0,
            outcome: None,
            lifecycle: String::new(),
            scope: None,
            before_snippet: None,
            after_snippet: None,
            provenances: Vec::new(),
        })
        .collect();
    Ok(responses)
}

/// Handle `POST /memories`
///
/// Creates or updates a memory from the request body.
///
/// Flow: build Memory from request DTO → save via service → return MemoryResponse.
///
/// ## Defaults
/// - `kind` defaults to "reference" if not specified
/// - `lifecycle` defaults to "new" if not specified
#[instrument(skip(service), fields(name = %req.name))]
pub fn handle_create_memory<M: MemoryService>(
    service: &M,
    req: MemoryCreateRequest,
) -> Result<MemoryResponse> {
    tracing::debug!("handling POST /memories for '{}'", req.name);
    let now = chrono::Utc::now().timestamp();
    let memory = Memory {
        name: req.name,
        description: req.description,
        content: req.content,
        kind: req.kind.unwrap_or_else(|| "reference".to_string()),
        created_at: now,
        updated_at: now,
        outcome: req.outcome,
        lifecycle: req.lifecycle.unwrap_or_else(|| "new".to_string()),
        scope: req.scope,
        before_snippet: req.before_snippet,
        after_snippet: req.after_snippet,
        provenances: req.provenances.unwrap_or_default(),
    };

    service
        .save_memory(&memory)
        .context("failed to save memory")?;

    Ok(MemoryResponse::from(memory))
}