use std::collections::HashSet;
use std::path::Path;

use crate::common::LcrConnError;

/// An item in the dataset.
#[derive(Clone, Debug)]
pub struct DatasetItem {
    /// The actual value of this item.
    pub value: f64,
    /// The string form of this value given from original input for re-saving.
    pub str_value: String,
}

impl DatasetItem {
    /// Create a new dataset item with validation.
    ///
    /// # Errors
    ///
    /// Returns [`LcrConnError::InvalidDatasetValue`] if the value is not greater than 0.
    /// Returns [`LcrConnError::EmptyDatasetItem`] if the string value is empty.
    pub fn new(value: f64, str_value: String) -> Result<Self, LcrConnError> {
        if value <= 0.0 {
            return Err(LcrConnError::InvalidDatasetValue(value));
        }
        if str_value.is_empty() {
            return Err(LcrConnError::EmptyDatasetItem);
        }
        Ok(Self { value, str_value })
    }
}

/// A list holding available standard values for resistor, capacitor or inductor.
///
/// Standard values is a collection of all possible values of specific device manufactured
/// by electronic factory. In reality, it also can be replaced by all possible values of
/// specific device provided by your laboratory. For example, your laboratory only provide
/// resistor with 100 Ohm and 4.7k Ohm. This list will only contain 100 and 4.7k.
pub struct Dataset {
    /// A list of available device gauge values.
    items: Vec<DatasetItem>,
}

impl Dataset {
    /// Create a dataset from an iterable of stringified values.
    ///
    /// # Errors
    ///
    /// Returns [`LcrConnError::DuplicateDatasetItem`] if duplicate values are found.
    /// Returns [`LcrConnError::EmptyDataset`] if the iterable produces no items.
    /// Returns [`LcrConnError::InvalidHumanReadableValue`] if a value cannot be parsed.
    pub fn from_iterable<I, S>(str_values: I) -> Result<Self, LcrConnError>
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        // Check string form value one by one
        let mut items: Vec<DatasetItem> = Vec::new();
        let mut seen: HashSet<f64> = HashSet::new();

        for str_value_raw in str_values {
            let str_value = str_value_raw.into();
            // Try parsing value
            let value = from_human_readable_value(&str_value)?;
            // Check and update set
            if !seen.insert(value) {
                return Err(LcrConnError::DuplicateDatasetItem(str_value));
            }
            // Add into result
            items.push(DatasetItem::new(value, str_value)?);
        }

        // Check empty case
        if items.is_empty() {
            return Err(LcrConnError::EmptyDataset);
        }

        // Ok, assign it
        Ok(Self { items })
    }

    /// Load a dataset from a block of text.
    ///
    /// Each non-empty line (after trimming whitespace) is treated as a value.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_iterable`].
    pub fn from_text(text: &str) -> Result<Self, LcrConnError> {
        let lines: Vec<String> = text
            .lines()
            .map(|line| line.trim().to_string())
            .filter(|line| !line.is_empty())
            .collect();
        Self::from_iterable(lines)
    }

    /// Load a dataset from a file.
    ///
    /// # Errors
    ///
    /// Returns [`LcrConnError::Io`] if the file cannot be read.
    /// See [`Dataset::from_iterable`] for other errors.
    pub fn from_file(path: impl AsRef<Path>) -> Result<Self, LcrConnError> {
        let text = std::fs::read_to_string(path)?;
        Self::from_text(&text)
    }

    /// The preset dataset for resistors.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_iterable`].
    pub fn resistor_preset() -> Result<Self, LcrConnError> {
        Self::from_iterable([
            "100", "220", "270", "390", "470", "680", "1k", "1.2k", "1.5k", "2.2k", "3.3k",
            "4.7k", "6.8k", "10k", "47k", "100k", "1M",
        ])
    }

    /// The preset dataset for capacitors.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_iterable`].
    pub fn capacitor_preset() -> Result<Self, LcrConnError> {
        Self::from_iterable([
            "10p", "22p", "33p", "47p", "68p", "100p", "150p", "220p", "330p", "470p", "560p",
            "1u", "2.2u", "3.3u", "4.7u", "10u", "22u", "47u", "100u", "220u", "470u",
        ])
    }

    /// The preset dataset for inductors.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_iterable`].
    pub fn inductor_preset() -> Result<Self, LcrConnError> {
        Self::from_iterable([
            "0.1u", "0.15u", "0.47u", "0.68u", "1u", "1.5u", "2.2u", "3.3u", "4.7u", "6.8u",
            "8.2u", "10u", "15u", "22u", "33u", "47u", "68u", "100u",
        ])
    }

    /// Get the string form of all values joined by newlines.
    pub fn save_text(&self) -> String {
        self.items
            .iter()
            .map(|i| i.str_value.as_str())
            .collect::<Vec<_>>()
            .join("\n")
    }

    /// Save all values to a file.
    ///
    /// # Errors
    ///
    /// Returns [`LcrConnError::Io`] if the file cannot be written.
    pub fn save_file(&self, path: impl AsRef<Path>) -> Result<(), LcrConnError> {
        std::fs::write(path, self.save_text())?;
        Ok(())
    }

    /// Get the available standard values as an iterator of `f64`.
    pub fn values(&self) -> impl Iterator<Item = f64> + '_ {
        self.items.iter().map(|i| i.value)
    }

    /// Get the underlying dataset items as a slice.
    pub fn items(&self) -> &[DatasetItem] {
        &self.items
    }
}

/// The collection holding all standard values for resistor, capacitor and inductor respectively.
pub struct DatasetCollection {
    /// A list of available device gauge values for resistor.
    resistor: Dataset,
    /// A list of available device gauge values for capacitor.
    capacitor: Dataset,
    /// A list of available device gauge values for inductor.
    inductor: Dataset,
}

impl DatasetCollection {
    pub fn new(resistor: Dataset, capacitor: Dataset, inductor: Dataset) -> Self {
        Self {
            resistor,
            capacitor,
            inductor,
        }
    }

    /// Load the standard values for resistor, capacitor and inductor respectively from iterables.
    ///
    /// # Arguments
    ///
    /// * `resistor` - The iterable to load available standard values for resistor.
    /// * `capacitor` - The iterable to load available standard values for capacitor.
    /// * `inductor` - The iterable to load available standard values for inductor.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_iterable`].
    pub fn from_iterable<I1, S1, I2, S2, I3, S3>(
        resistor: I1,
        capacitor: I2,
        inductor: I3,
    ) -> Result<Self, LcrConnError>
    where
        I1: IntoIterator<Item = S1>,
        S1: Into<String>,
        I2: IntoIterator<Item = S2>,
        S2: Into<String>,
        I3: IntoIterator<Item = S3>,
        S3: Into<String>,
    {
        Ok(Self {
            resistor: Dataset::from_iterable(resistor)?,
            capacitor: Dataset::from_iterable(capacitor)?,
            inductor: Dataset::from_iterable(inductor)?,
        })
    }

    /// Load the standard values from strings.
    ///
    /// # Arguments
    ///
    /// * `resistor` - The string to load available standard values for resistor.
    /// * `capacitor` - The string to load available standard values for capacitor.
    /// * `inductor` - The string to load available standard values for inductor.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_text`].
    pub fn from_text(resistor: &str, capacitor: &str, inductor: &str) -> Result<Self, LcrConnError> {
        Ok(Self {
            resistor: Dataset::from_text(resistor)?,
            capacitor: Dataset::from_text(capacitor)?,
            inductor: Dataset::from_text(inductor)?,
        })
    }

    /// Load the standard values from files.
    ///
    /// # Arguments
    ///
    /// * `resistor` - The file to load available standard values for resistor.
    /// * `capacitor` - The file to load available standard values for capacitor.
    /// * `inductor` - The file to load available standard values for inductor.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_file`].
    pub fn from_file(
        resistor: impl AsRef<Path>,
        capacitor: impl AsRef<Path>,
        inductor: impl AsRef<Path>,
    ) -> Result<Self, LcrConnError> {
        Ok(Self {
            resistor: Dataset::from_file(resistor)?,
            capacitor: Dataset::from_file(capacitor)?,
            inductor: Dataset::from_file(inductor)?,
        })
    }

    /// The preset dataset collection for all devices.
    ///
    /// # Errors
    ///
    /// See [`Dataset::from_iterable`].
    pub fn devices_preset() -> Result<Self, LcrConnError> {
        Ok(Self {
            resistor: Dataset::resistor_preset()?,
            capacitor: Dataset::capacitor_preset()?,
            inductor: Dataset::inductor_preset()?,
        })
    }

    /// Get the string form of all values.
    ///
    /// # Returns
    ///
    /// A tuple of strings for resistor, capacitor and inductor respectively.
    pub fn save_text(&self) -> (String, String, String) {
        (
            self.resistor.save_text(),
            self.capacitor.save_text(),
            self.inductor.save_text(),
        )
    }

    /// Save all values to files.
    ///
    /// # Arguments
    ///
    /// * `resistor` - The file to save available standard values for resistor.
    /// * `capacitor` - The file to save available standard values for capacitor.
    /// * `inductor` - The file to save available standard values for inductor.
    ///
    /// # Errors
    ///
    /// Returns [`LcrConnError::Io`] if any file cannot be written.
    pub fn save_file(
        &self,
        resistor: impl AsRef<Path>,
        capacitor: impl AsRef<Path>,
        inductor: impl AsRef<Path>,
    ) -> Result<(), LcrConnError> {
        self.resistor.save_file(resistor)?;
        self.capacitor.save_file(capacitor)?;
        self.inductor.save_file(inductor)?;
        Ok(())
    }

    /// Get the dataset for resistor.
    pub fn resistor(&self) -> &Dataset {
        &self.resistor
    }

    /// Get the dataset for capacitor.
    pub fn capacitor(&self) -> &Dataset {
        &self.capacitor
    }

    /// Get the dataset for inductor.
    pub fn inductor(&self) -> &Dataset {
        &self.inductor
    }
}

/// Convert human readable value to float.
///
/// # Arguments
///
/// * `strl` - The human readable value.
///
/// # Returns
///
/// The parsed float value.
///
/// # Errors
///
/// Returns [`LcrConnError::InvalidHumanReadableValue`] if the input string is not a valid number.
pub fn from_human_readable_value(strl: &str) -> Result<f64, LcrConnError> {
    let strl = strl.trim();

    let (num_part, multiplier) = if let Some(stripped) = strl.strip_suffix('n') {
        (stripped, 1e-12)
    } else if let Some(stripped) = strl.strip_suffix('p') {
        (stripped, 1e-9)
    } else if let Some(stripped) = strl.strip_suffix('u') {
        (stripped, 1e-6)
    } else if let Some(stripped) = strl.strip_suffix('m') {
        (stripped, 1e-3)
    } else if let Some(stripped) = strl.strip_suffix('k') {
        (stripped, 1e3)
    } else if let Some(stripped) = strl.strip_suffix('M') {
        (stripped, 1e6)
    } else if let Some(stripped) = strl.strip_suffix('G') {
        (stripped, 1e9)
    } else {
        (strl, 1.0)
    };

    num_part
        .parse::<f64>()
        .map(|v| v * multiplier)
        .map_err(|_| LcrConnError::InvalidHumanReadableValue(strl.to_string()))
}

/// The unit scale for human readable value.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum UnitScale {
    NanoLower,
    Nano,
    Micro,
    Milli,
    None,
    Kilo,
    Mega,
    Giga,
    GigaHigher,
}

/// Get the unit scale of human readable value.
///
/// # Arguments
///
/// * `v` - The value.
///
/// # Returns
///
/// The unit scale.
pub fn get_human_readable_value_scale(v: f64) -> UnitScale {
    let v = v.abs();
    if v < 1e-12 {
        UnitScale::NanoLower
    } else if v < 1e-9 {
        UnitScale::Nano
    } else if v < 1e-6 {
        UnitScale::Micro
    } else if v < 1e-3 {
        UnitScale::Milli
    } else if v < 1e3 {
        UnitScale::None
    } else if v < 1e6 {
        UnitScale::Kilo
    } else if v < 1e9 {
        UnitScale::Mega
    } else if v < 1e12 {
        UnitScale::Giga
    } else {
        UnitScale::GigaHigher
    }
}

/// Convert float value to human readable value.
///
/// # Arguments
///
/// * `v` - The float value.
///
/// # Returns
///
/// The human readable value.
pub fn to_human_readable_value(v: f64) -> String {
    let scale = get_human_readable_value_scale(v);
    match scale {
        UnitScale::NanoLower => format!("{:+.4e} n", v / 1e-12),
        UnitScale::Nano => format!("{:+.4f} p", v / 1e-9),
        UnitScale::Micro => format!("{:+.4f} u", v / 1e-6),
        UnitScale::Milli => format!("{:+.4f} m", v / 1e-3),
        UnitScale::None => {
            // YYC MARK:
            // The space of this format string is by design
            // for keeping the same style with other format strings.
            format!("{:+.4} ", v)
        }
        UnitScale::Kilo => format!("{:+.4f} k", v / 1e3),
        UnitScale::Mega => format!("{:+.4f} M", v / 1e6),
        UnitScale::Giga => format!("{:+.4f} G", v / 1e9),
        UnitScale::GigaHigher => format!("{:+.4e} G", v / 1e9),
    }
}