use std::collections::BTreeMap;
use std::io::{self, Write};
use std::path::{Path, PathBuf};
use std::process::ExitCode;

use provider::catalog::{self, AuthHint, ModelEntry, ProviderEntry};
use toml::Value;
use toml::map::Map;

const GENERATED_PROFILE_NAME: &str = "default";
const GENERATED_PROFILE_PATH: &str = "profiles/default.lua";
const GENERATED_PROFILE_DESCRIPTION: &str = "Generated by yoi setup-model";

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ModelChoice {
    pub model_ref: String,
    pub provider_id: String,
    pub provider_display_name: String,
    pub model_id: String,
    pub auth_hint: AuthHint,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct WrittenSetupConfig {
    pub registry_path: PathBuf,
    pub profile_path: PathBuf,
    pub model_ref: String,
}

pub async fn launch() -> ExitCode {
    match run_interactive_setup() {
        Ok(written) => {
            println!(
                "Saved default Profile `{}` for model `{}`",
                GENERATED_PROFILE_NAME, written.model_ref
            );
            println!("registry: {}", written.registry_path.display());
            println!("profile:  {}", written.profile_path.display());
            ExitCode::SUCCESS
        }
        Err(err) => {
            eprintln!("yoi setup-model: {err}");
            ExitCode::FAILURE
        }
    }
}

fn run_interactive_setup() -> Result<WrittenSetupConfig, Box<dyn std::error::Error>> {
    let config_dir = manifest::paths::config_dir().ok_or_else(|| {
        io::Error::new(
            io::ErrorKind::NotFound,
            "could not determine yoi config directory",
        )
    })?;
    let choices = load_model_choices()?;
    let choice = prompt_model_choice(&choices)?;
    write_default_profile_config(&config_dir, &choice.model_ref)
}

pub fn load_model_choices() -> Result<Vec<ModelChoice>, catalog::CatalogError> {
    let providers = catalog::load_providers()?
        .into_iter()
        .map(|provider| (provider.id.clone(), provider))
        .collect::<BTreeMap<_, _>>();
    let mut choices = catalog::load_models()?
        .into_iter()
        .filter_map(|model| choice_from_model(model, &providers))
        .collect::<Vec<_>>();
    choices.sort_by(|a, b| {
        a.provider_display_name
            .cmp(&b.provider_display_name)
            .then_with(|| a.model_id.cmp(&b.model_id))
            .then_with(|| a.model_ref.cmp(&b.model_ref))
    });
    Ok(choices)
}

fn choice_from_model(
    model: ModelEntry,
    providers: &BTreeMap<String, ProviderEntry>,
) -> Option<ModelChoice> {
    let provider = providers.get(&model.provider)?;
    Some(ModelChoice {
        model_ref: format!("{}/{}", model.provider, model.id),
        provider_id: provider.id.clone(),
        provider_display_name: provider.display_name.clone(),
        model_id: model.id,
        auth_hint: provider.auth_hint.clone(),
    })
}

fn prompt_model_choice(
    choices: &[ModelChoice],
) -> Result<&ModelChoice, Box<dyn std::error::Error>> {
    if choices.is_empty() {
        return Err("no models are configured in the model catalog".into());
    }

    println!("yoi setup-model");
    println!();
    println!("Choose the default model Profile to write under the user config directory.");
    println!("This command only writes Profile config; it does not start or attach a Pod.");
    println!();
    for (idx, choice) in choices.iter().enumerate() {
        println!(
            "{:>2}. {:<42} {} ({})",
            idx + 1,
            choice.model_ref,
            choice.provider_display_name,
            auth_hint_label(&choice.auth_hint),
        );
    }
    println!();
    print!("Select model [1]: ");
    io::stdout().flush()?;

    let mut input = String::new();
    io::stdin().read_line(&mut input)?;
    let selection = input.trim();
    let index = if selection.is_empty() {
        0
    } else {
        selection
            .parse::<usize>()
            .map_err(|_| format!("invalid model selection `{selection}`"))?
            .checked_sub(1)
            .ok_or("model selection starts at 1")?
    };
    choices
        .get(index)
        .ok_or_else(|| format!("model selection {} is out of range", index + 1).into())
}

fn auth_hint_label(hint: &AuthHint) -> String {
    match hint {
        AuthHint::None => "no auth".to_string(),
        AuthHint::ApiKey => "API key file".to_string(),
        AuthHint::SecretRef { ref_ } => format!("secret `{ref_}`"),
        AuthHint::CodexOAuth => "Codex OAuth".to_string(),
    }
}

pub fn write_default_profile_config(
    config_dir: &Path,
    model_ref: &str,
) -> Result<WrittenSetupConfig, Box<dyn std::error::Error>> {
    std::fs::create_dir_all(config_dir)?;
    let profiles_dir = config_dir.join("profiles");
    std::fs::create_dir_all(&profiles_dir)?;

    let profile_path = config_dir.join(GENERATED_PROFILE_PATH);
    std::fs::write(&profile_path, generated_profile_lua(model_ref))?;

    let registry_path = config_dir.join("profiles.toml");
    let mut document = read_registry_document(&registry_path)?;
    set_default_profile_entry(&mut document)?;
    std::fs::write(&registry_path, toml::to_string_pretty(&document)?)?;

    Ok(WrittenSetupConfig {
        registry_path,
        profile_path,
        model_ref: model_ref.to_string(),
    })
}

fn read_registry_document(path: &Path) -> Result<Value, Box<dyn std::error::Error>> {
    if !path.exists() {
        return Ok(Value::Table(Map::new()));
    }
    let text = std::fs::read_to_string(path)?;
    let value: Value = toml::from_str(&text)?;
    if !value.is_table() {
        return Err(format!("{} must contain a TOML table", path.display()).into());
    }
    Ok(value)
}

fn set_default_profile_entry(document: &mut Value) -> Result<(), Box<dyn std::error::Error>> {
    let table = document
        .as_table_mut()
        .ok_or("profiles.toml root must be a TOML table")?;
    table.insert(
        "default".to_string(),
        Value::String(format!("user:{GENERATED_PROFILE_NAME}")),
    );

    let profile_value = table
        .entry("profile".to_string())
        .or_insert_with(|| Value::Table(Map::new()));
    let profile_table = profile_value
        .as_table_mut()
        .ok_or("profiles.toml `profile` must be a TOML table")?;
    let mut entry = Map::new();
    entry.insert(
        "path".to_string(),
        Value::String(GENERATED_PROFILE_PATH.to_string()),
    );
    entry.insert(
        "description".to_string(),
        Value::String(GENERATED_PROFILE_DESCRIPTION.to_string()),
    );
    profile_table.insert(GENERATED_PROFILE_NAME.to_string(), Value::Table(entry));
    Ok(())
}

fn generated_profile_lua(model_ref: &str) -> String {
    format!(
        r#"local profile = require("yoi.profile")
local scope = require("yoi.scope")
local compact = require("yoi.compact")

return profile {{
    slug = "default",
    description = "Generated by yoi setup-model",

    scope = scope.workspace_write(),

    session = {{
        record_event_trace = true,
    }},

    worker = {{
        reasoning = "high",
    }},

    model = {{
        ref = "{}",
    }},

    compaction = compact.tokens {{
        threshold = 240000,
        request_threshold = 270000,
        worker_context_max_tokens = 100000,
    }},

    feature = {{
        task = {{ enabled = true }},
        memory = {{ enabled = true }},
        web = {{ enabled = true }},
        pods = {{ enabled = false }},
        ticket = {{ enabled = false, access = "lifecycle" }},
        ticket_orchestration = {{ enabled = false }},
    }},

    memory = {{
        extract_threshold = 50000,
        consolidation_threshold_files = 5,
        consolidation_threshold_bytes = 50000,
    }},

    web = {{
        enabled = true,
        search = {{
            provider = "brave",
            api_key_secret = "web/brave/default",
        }},
    }},
}}
"#,
        escape_lua_string(model_ref)
    )
}

fn escape_lua_string(value: &str) -> String {
    value
        .chars()
        .flat_map(|c| match c {
            '\\' => "\\\\".chars().collect::<Vec<_>>(),
            '"' => "\\\"".chars().collect::<Vec<_>>(),
            '\n' => "\\n".chars().collect::<Vec<_>>(),
            '\r' => "\\r".chars().collect::<Vec<_>>(),
            '\t' => "\\t".chars().collect::<Vec<_>>(),
            other => vec![other],
        })
        .collect()
}

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

    #[test]
    fn write_default_profile_config_creates_registry_and_profile() {
        let dir = tempfile::tempdir().unwrap();

        let written = write_default_profile_config(dir.path(), "codex-oauth/gpt-5.5").unwrap();

        assert_eq!(written.registry_path, dir.path().join("profiles.toml"));
        assert_eq!(
            written.profile_path,
            dir.path().join("profiles/default.lua")
        );

        let registry = std::fs::read_to_string(&written.registry_path).unwrap();
        assert!(registry.contains("default = \"user:default\""));
        assert!(registry.contains("[profile.default]"));
        assert!(registry.contains("path = \"profiles/default.lua\""));

        let profile = std::fs::read_to_string(&written.profile_path).unwrap();
        assert!(profile.contains("slug = \"default\""));
        assert!(profile.contains("ref = \"codex-oauth/gpt-5.5\""));
        assert!(profile.contains("scope = scope.workspace_write()"));
    }

    #[test]
    fn write_default_profile_config_preserves_other_profile_entries() {
        let dir = tempfile::tempdir().unwrap();
        std::fs::write(
            dir.path().join("profiles.toml"),
            r#"[profile.other]
path = "profiles/other.lua"
description = "keep me"
"#,
        )
        .unwrap();

        write_default_profile_config(dir.path(), "anthropic/claude-sonnet-4-6").unwrap();

        let registry = std::fs::read_to_string(dir.path().join("profiles.toml")).unwrap();
        assert!(registry.contains("[profile.other]"));
        assert!(registry.contains("path = \"profiles/other.lua\""));
        assert!(registry.contains("[profile.default]"));
        assert!(registry.contains("default = \"user:default\""));
    }

    #[test]
    fn escape_lua_string_escapes_quotes_and_slashes() {
        assert_eq!(escape_lua_string("a\\b\"c"), "a\\\\b\\\"c");
    }
}