//! Azure Blob Storage: `az://ACCOUNT/CONTAINER/PREFIX`.

//!

//! Credentials: a service principal (`AZURE_CLIENT_ID`,

//! `AZURE_CLIENT_SECRET`, `AZURE_TENANT_ID`, as the Azure SDKs name them,

//! or the `AZURE_STORAGE_*` spellings), an account key

//! (`AZURE_STORAGE_ACCOUNT_KEY`), a SAS token (`AZURE_STORAGE_SAS_TOKEN`),

//! else what `az login` left behind, else the machine's managed

//! identity. `?endpoint=URL` points at an emulator.

use crate::StoreUrl;

use object_store::azure::{MicrosoftAzure, MicrosoftAzureBuilder};

use oxy_core::strata::{Error, Result};

pub const HINT: &str = "run `az login`, or set AZURE_CLIENT_ID, AZURE_CLIENT_SECRET and AZURE_TENANT_ID for a service principal, or AZURE_STORAGE_ACCOUNT_KEY";

fn env(name: &str) -> Option<String> {

    std::env::var(name).ok().filter(|v| !v.is_empty())

}

/// The store and the prefix under the container.

pub fn open(url: &StoreUrl) -> Result<(MicrosoftAzure, String)> {

    let (container, prefix) = match url.path.split_once('/') {

        Some((c, p)) => (c.to_string(), p.to_string()),

        None if !url.path.is_empty() => (url.path.clone(), String::new()),

        None => {

            return Err(Error::Backend(format!(

                "{}: an Azure store URL names the account and the container: az://ACCOUNT/CONTAINER/PREFIX",

                url.plain()

            )))

        }

    };

    let mut b = MicrosoftAzureBuilder::from_env()

        .with_account(&url.host)

        .with_container_name(&container);

    let principal = (

        env("AZURE_CLIENT_ID").or_else(|| env("AZURE_STORAGE_CLIENT_ID")),

        env("AZURE_CLIENT_SECRET").or_else(|| env("AZURE_STORAGE_CLIENT_SECRET")),

        env("AZURE_TENANT_ID").or_else(|| env("AZURE_STORAGE_TENANT_ID")),

    );

    let mut explicit = false;

    if let (Some(id), Some(secret), Some(tenant)) = principal {

        b = b.with_client_secret_authorization(id, secret, tenant);

        explicit = true;

    }

    if env("AZURE_STORAGE_ACCOUNT_KEY").is_some()

        || env("AZURE_STORAGE_ACCESS_KEY").is_some()

        || env("AZURE_STORAGE_SAS_TOKEN").is_some()

        || env("AZURE_STORAGE_SAS_KEY").is_some()

    {

        explicit = true;

    }

    if let Some(endpoint) = url.param("endpoint") {

        b = b

            .with_endpoint(endpoint.to_string())

            .with_allow_http(endpoint.starts_with("http://"));

    }

    if !explicit {

        // What `az login` left behind; the managed identity comes after.

        b = b.with_use_azure_cli(true);

    }

    let store = b

        .build()

        .map_err(|e| Error::Backend(format!("{}: {e}: {HINT}", url.plain())))?;

    Ok((store, prefix))

}