use crate::cli::Cli;
use crate::generator::config::{
    Config as GeneratorConfig, ProvidedConfig as ProvidedGeneratorConfig,
};
use crate::parser::clang::config::{Config as ClangConfig, ProvidedConfig as ProvidedClangConfig};

use anyhow::{anyhow, Context, Result};
use codemap::CodeMap;
use codemap_diagnostic::Diagnostic;
use serde_derive::{Deserialize, Serialize};
use structopt::StructOpt;
use thiserror::Error;

use std::path::{Path, PathBuf};
use std::sync::Arc;

pub(super) const DEFAULT_PROJECT_CONFIGURATION_FILE_NAME: &str = "poseidoc.toml";

#[derive(Debug, Clone, Serialize)]
pub(crate) struct Config {
    pub(crate) name: String,
    pub(crate) generator: GeneratorConfig,
    pub(crate) clang: ClangConfig,
}

impl Default for Config {
    fn default() -> Self {
        Config {
            name: String::from("My Project"),
            clang: ClangConfig::default(),
            generator: GeneratorConfig::default(),
        }
    }
}

impl Config {
    pub(crate) fn from_merge(cli: Cli, conf: ProvidedConfig) -> Result<Self> {
        Ok(Config {
            name: cli
                .common_options
                .name
                .or(conf.name)
                .unwrap_or_else(|| String::from("My Project")),
            clang: ClangConfig::from_merge(cli.common_options.clang, conf.clang)?,
            generator: GeneratorConfig::from_merge(cli.common_options.generator, conf.generator),
        })
    }
}

/// Same as ProvidedConfig but with options for when not user-provided
#[derive(Debug, Clone, Default, StructOpt, Deserialize)]
#[structopt(rename_all = "kebab-case")]
#[serde(rename_all = "kebab-case")]
pub(crate) struct ProvidedConfig {
    #[structopt(skip)]
    pub(crate) name: Option<String>,
    #[structopt(flatten)]
    #[serde(default)]
    pub(crate) clang: ProvidedClangConfig,
    #[structopt(flatten)]
    #[serde(default)]
    pub(crate) generator: ProvidedGeneratorConfig,
}

pub(super) fn load_config(
    location: impl AsRef<Path>,
    codemap: &mut CodeMap,
) -> Result<ProvidedConfig> {
    let location = location.as_ref();

    let final_path = if location.is_dir() {
        location.join(DEFAULT_PROJECT_CONFIGURATION_FILE_NAME)
    } else if !location.exists() {
        return Err(anyhow!("File {:?} does not exists", location))
            .with_context(|| format!("Failed to open project configuration: {:?}", location));
    } else {
        location.to_owned()
    };

    let config_str =
        std::fs::read_to_string(&final_path).map_err(|err| ConfigLoadError::IoError {
            file_name: final_path.clone(),
            source: err,
        })?;
    Ok(
        toml::from_str(&config_str).map_err(|err| ConfigLoadError::TomlDeserialzation {
            file: codemap.add_file(final_path.to_string_lossy().into(), config_str),
            source: err,
        })?,
    )
}

#[derive(Debug, Error)]
#[error("Error loading project configuration")]
pub(crate) enum ConfigLoadError {
    #[error("Failed to read project configuration: {:?}", file_name)]
    IoError {
        file_name: PathBuf,
        source: std::io::Error,
    },
    #[error("Failed to parse project configuration: {:?}", file.name())]
    TomlDeserialzation {
        file: Arc<codemap::File>,
        source: toml::de::Error,
    },
}

impl From<&ConfigLoadError> for Diagnostic {
    fn from(err: &ConfigLoadError) -> Diagnostic {
        use codemap_diagnostic::{Level, SpanLabel, SpanStyle};
        use std::convert::TryInto;

        let message = err.to_string();

        let spans = match err {
            ConfigLoadError::IoError { .. } => vec![],
            ConfigLoadError::TomlDeserialzation { file, source, .. } => {
                if let Some((line, col)) = source.line_col() {
                    let line_span = file.line_span(line);
                    let col = col.try_into().unwrap();
                    let span = line_span.subspan(col, col);
                    vec![SpanLabel {
                        span,
                        label: None,
                        style: SpanStyle::Primary,
                    }]
                } else {
                    vec![]
                }
            }
        };

        Diagnostic {
            level: Level::Error,
            message,
            code: None,
            spans,
        }
    }
}