//! FIXME discuss about which errors to print and when to panic

use std::{collections::HashMap, iter::FilterMap, path::Path, slice::Iter};

const SUPPORTED_FAMILIES: [&str; 8] = [
    "stm32f0",
    "stm32f4",
    "stm32g0",
    "stm32l0",
    "stm32l4",
    "stm32h7",
    "stm32wb55",
    "stm32wl55",
];

const SEPARATOR_START: &str = "# BEGIN GENERATED FEATURES\n";
const SEPARATOR_END: &str = "# END GENERATED FEATURES\n";
const HELP: &str = "# Generated by stm32-gen-features. DO NOT EDIT.\n";

/// True if the chip named `name` is supported else false
fn is_supported(name: &str) -> bool {
    SUPPORTED_FAMILIES
        .iter()
        .any(|family| name.starts_with(family))
}

type SupportedIter<'a> = FilterMap<
    Iter<'a, (String, Vec<String>)>,
    fn(&(String, Vec<String>)) -> Option<(&String, &Vec<String>)>,
>;
trait FilterSupported {
    fn supported(&self) -> SupportedIter;
}
impl FilterSupported for &[(String, Vec<String>)] {
    /// Get a new Vec with only the supported chips
    fn supported(&self) -> SupportedIter {
        self.iter()
            .filter_map(|(name, cores)| is_supported(name).then(|| (name, cores)))
    }
}

/// Get the list of all the chips and their supported cores
///
/// Print errors to `stderr` when something is returned by the glob but is not in the returned
/// [`Vec`]
///
/// This function is slow because all the yaml files are parsed.
pub fn chip_names_and_cores() -> Vec<(String, Vec<String>)> {
    glob::glob("../stm32-data/data/chips/*.yaml")
        .unwrap()
        .filter_map(|entry| entry.map_err(|e| eprintln!("{:?}", e)).ok())
        .filter_map(|entry| {
            if let Some(name) = entry.file_stem().and_then(|stem| stem.to_str()) {
                Some((name.to_lowercase(), chip_cores(&entry)))
            } else {
                eprintln!("{:?} is not a regular file", entry);
                None
            }
        })
        .collect()
}

/// Get the list of the cores of a chip by its associated file
///
/// # Panic
/// Panics if the file does not exist or if it contains yaml syntax errors.
/// Panics if "cores" is not an array.
fn chip_cores(path: &Path) -> Vec<String> {
    let file_contents = std::fs::read_to_string(path).unwrap();
    let doc = &yaml_rust::YamlLoader::load_from_str(&file_contents).unwrap()[0];
    doc["cores"]
        .as_vec()
        .unwrap_or_else(|| panic!("{:?}:[cores] is not an array", path))
        .iter()
        .enumerate()
        .map(|(i, core)| {
            core["name"]
                .as_str()
                .unwrap_or_else(|| panic!("{:?}:[cores][{}][name] is not a string", path, i))
                .to_owned()
        })
        .collect()
}

/// Generate data needed in `../embassy-stm32/Cargo.toml`
///
/// Print errors to `stderr` when something is returned by the glob but is not in the returned
/// [`Vec`]
///
/// # Panic
/// Panics if a file contains yaml syntax errors or if a value does not have a consistent type
pub fn embassy_stm32_needed_data(
    names_and_cores: &[(String, Vec<String>)],
) -> HashMap<String, Vec<String>> {
    let mut result = HashMap::new();
    for (chip_name, cores) in names_and_cores.supported() {
        if cores.len() > 1 {
            for core_name in cores.iter() {
                let key = format!("{}_{}", chip_name, core_name);
                let value = vec![format!("stm32-metapac/{}_{}", chip_name, core_name)];
                result.insert(key, value);
            }
        } else {
            let key = chip_name.to_string();
            let value = vec![format!("stm32-metapac/{}", chip_name)];
            result.insert(key, value);
        }
    }
    result
}

/// Generate data needed in `../stm32-metapac/Cargo.toml`
///
/// Print errors to `stderr` when something is returned by the glob but is not in the returned
/// [`Vec`]
///
/// # Panic
/// Panics if a file contains yaml syntax errors or if a value does not have a consistent type
pub fn stm32_metapac_needed_data(
    names_and_cores: &[(String, Vec<String>)],
) -> HashMap<String, Vec<String>> {
    let mut result = HashMap::new();
    for (chip_name, cores) in names_and_cores {
        if cores.len() > 1 {
            for core_name in cores {
                let key = format!("{}_{}", chip_name, core_name);
                result.insert(key, vec![]);
            }
        } else {
            result.insert(chip_name.clone(), vec![]);
        }
    }
    result
}

/// Get contents before and after generated contents
///
/// # Panic
/// Panics when a separator cound not be not found
fn split_cargo_toml_contents(contents: &str) -> (&str, &str) {
    let (before, remainder) = contents
        .split_once(SEPARATOR_START)
        .unwrap_or_else(|| panic!("missing \"{}\" tag", SEPARATOR_START));
    let (_, after) = remainder
        .split_once(SEPARATOR_END)
        .unwrap_or_else(|| panic!("missing \"{}\" tag", SEPARATOR_END));

    (before, after)
}

/// Generates new contents for Cargo.toml
///
/// # Panic
/// Panics when a separator cound not be not found
pub fn generate_cargo_toml_file(
    previous_text: &str,
    new_contents: &HashMap<String, Vec<String>>,
) -> String {
    let (before, after) = split_cargo_toml_contents(previous_text);
    let generated_content = toml::to_string(new_contents).unwrap();
    before.to_owned() + SEPARATOR_START + HELP + &generated_content + SEPARATOR_END + after
}

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

    #[test]
    fn stm32f407vg_is_supported() {
        assert!(is_supported("stm32f407vg"))
    }

    #[test]
    fn abcdef_is_not_supported() {
        assert!(!is_supported("abcdef"))
    }

    #[test]
    #[ignore]
    fn stm32f407vg_yaml_file_exists_and_is_supported() {
        assert!(chip_names_and_cores()
            .as_slice()
            .supported()
            .into_iter()
            .any(|(name, _)| { name == "stm32f407vg" }))
    }

    #[test]
    fn keeps_text_around_separators() {
        let initial = "\
before
# BEGIN GENERATED FEATURES
# END GENERATED FEATURES
after
";

        let expected = "\
before
# BEGIN GENERATED FEATURES
# Generated by stm32-gen-features. DO NOT EDIT.
a = [\"b\"]
# END GENERATED FEATURES
after
";

        let map = HashMap::from([(String::from("a"), vec![String::from("b")])]);
        assert_eq!(generate_cargo_toml_file(initial, &map), expected);
    }

    #[test]
    #[should_panic]
    fn does_not_generate_if_separators_are_missing() {
        let initial = "\
before
# END GENERATED FEATURES
after
";

        let map = HashMap::from([(String::from("a"), vec![String::from("b")])]);
        generate_cargo_toml_file(initial, &map);
    }
}