//! Configuration module for timer sensor
//!
//! Supports loading configuration from environment variables or stdin JSON.

use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::io::Read;

/// Sensor configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SensorConfig {
    /// Base URL of the Attune API
    pub api_url: String,

    /// API token for authentication
    pub api_token: String,

    /// Sensor reference name (e.g., "core.timer")
    pub sensor_ref: String,

    /// RabbitMQ connection URL
    pub mq_url: String,

    /// RabbitMQ exchange name (default: "attune")
    #[serde(default = "default_exchange")]
    pub mq_exchange: String,

    /// Log level (default: "info")
    #[serde(default = "default_log_level")]
    pub log_level: String,
}

fn default_exchange() -> String {
    "attune".to_string()
}

fn default_log_level() -> String {
    "info".to_string()
}

impl SensorConfig {
    /// Load configuration from environment variables
    pub fn from_env() -> Result<Self> {
        let api_url = std::env::var("ATTUNE_API_URL")
            .context("ATTUNE_API_URL environment variable is required")?;

        let api_token = std::env::var("ATTUNE_API_TOKEN")
            .context("ATTUNE_API_TOKEN environment variable is required")?;

        let sensor_ref = std::env::var("ATTUNE_SENSOR_REF")
            .context("ATTUNE_SENSOR_REF environment variable is required")?;

        let mq_url = std::env::var("ATTUNE_MQ_URL")
            .context("ATTUNE_MQ_URL environment variable is required")?;

        let mq_exchange =
            std::env::var("ATTUNE_MQ_EXCHANGE").unwrap_or_else(|_| default_exchange());

        let log_level = std::env::var("ATTUNE_LOG_LEVEL").unwrap_or_else(|_| default_log_level());

        Ok(Self {
            api_url,
            api_token,
            sensor_ref,
            mq_url,
            mq_exchange,
            log_level,
        })
    }

    /// Load configuration from stdin JSON
    pub async fn from_stdin() -> Result<Self> {
        let mut buffer = String::new();
        std::io::stdin()
            .read_to_string(&mut buffer)
            .context("Failed to read configuration from stdin")?;

        serde_json::from_str(&buffer).context("Failed to parse JSON configuration from stdin")
    }

    /// Validate configuration
    pub fn validate(&self) -> Result<()> {
        if self.api_url.is_empty() {
            return Err(anyhow::anyhow!("api_url cannot be empty"));
        }

        if self.api_token.is_empty() {
            return Err(anyhow::anyhow!("api_token cannot be empty"));
        }

        if self.sensor_ref.is_empty() {
            return Err(anyhow::anyhow!("sensor_ref cannot be empty"));
        }

        if self.mq_url.is_empty() {
            return Err(anyhow::anyhow!("mq_url cannot be empty"));
        }

        if self.mq_exchange.is_empty() {
            return Err(anyhow::anyhow!("mq_exchange cannot be empty"));
        }

        // Validate API URL format
        if !self.api_url.starts_with("http://") && !self.api_url.starts_with("https://") {
            return Err(anyhow::anyhow!(
                "api_url must start with http:// or https://"
            ));
        }

        // Validate MQ URL format
        if !self.mq_url.starts_with("amqp://") && !self.mq_url.starts_with("amqps://") {
            return Err(anyhow::anyhow!(
                "mq_url must start with amqp:// or amqps://"
            ));
        }

        Ok(())
    }
}

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

    #[test]
    fn test_config_validation() {
        let config = SensorConfig {
            api_url: "http://localhost:8080".to_string(),
            api_token: "test_token".to_string(),
            sensor_ref: "core.timer".to_string(),
            mq_url: "amqp://localhost:5672".to_string(),
            mq_exchange: "attune".to_string(),
            log_level: "info".to_string(),
        };

        assert!(config.validate().is_ok());
    }

    #[test]
    fn test_config_validation_invalid_api_url() {
        let config = SensorConfig {
            api_url: "localhost:8080".to_string(), // Missing http://
            api_token: "test_token".to_string(),
            sensor_ref: "core.timer".to_string(),
            mq_url: "amqp://localhost:5672".to_string(),
            mq_exchange: "attune".to_string(),
            log_level: "info".to_string(),
        };

        assert!(config.validate().is_err());
    }

    #[test]
    fn test_config_validation_invalid_mq_url() {
        let config = SensorConfig {
            api_url: "http://localhost:8080".to_string(),
            api_token: "test_token".to_string(),
            sensor_ref: "core.timer".to_string(),
            mq_url: "localhost:5672".to_string(), // Missing amqp://
            mq_exchange: "attune".to_string(),
            log_level: "info".to_string(),
        };

        assert!(config.validate().is_err());
    }

    #[test]
    fn test_config_deserialization() {
        let json = r#"{
            "api_url": "http://localhost:8080",
            "api_token": "test_token",
            "sensor_ref": "core.timer",
            "mq_url": "amqp://localhost:5672"
        }"#;

        let config: SensorConfig = serde_json::from_str(json).unwrap();
        assert_eq!(config.api_url, "http://localhost:8080");
        assert_eq!(config.api_token, "test_token");
        assert_eq!(config.sensor_ref, "core.timer");
        assert_eq!(config.mq_url, "amqp://localhost:5672");
        assert_eq!(config.mq_exchange, "attune"); // Default
        assert_eq!(config.log_level, "info"); // Default
    }

    #[test]
    fn test_config_deserialization_with_optionals() {
        let json = r#"{
            "api_url": "http://localhost:8080",
            "api_token": "test_token",
            "sensor_ref": "core.timer",
            "mq_url": "amqp://localhost:5672",
            "mq_exchange": "custom",
            "log_level": "debug"
        }"#;

        let config: SensorConfig = serde_json::from_str(json).unwrap();
        assert_eq!(config.mq_exchange, "custom");
        assert_eq!(config.log_level, "debug");
    }
}