// SPDX-FileCopyrightText: OpenTalk GmbH <mail@opentalk.eu>
// SPDX-License-Identifier: MIT OR Apache-2.0

use std::ops::Deref;

use serde::{de::Error as _, Deserialize, Deserializer, Serialize};

/// Enum type for defining the possible output file formats
#[derive(
    Debug,
    Clone,
    PartialEq,
    Eq,
    Serialize,
    Deserialize,
    strum::AsRefStr,
    strum::Display,
    strum::EnumCount,
    strum::EnumIter,
    strum::EnumString,
    strum::VariantNames,
    strum::IntoStaticStr,
)]
#[serde(rename_all = "snake_case")]
#[strum(serialize_all = "snake_case")]
#[serde(tag = "format")]
pub enum OutputFormat {
    /// The PDF file format
    Pdf {
        /// Specifies the program that is used to render the PDF document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        engine: PdfEngine,

        /// The theme which should be used for the rendered document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        theme: Option<Theme>,
    },

    /// Microsoft Office Open XML docx format
    Docx {
        /// The theme which should be used for the rendered document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        theme: Option<Theme>,
    },

    /// OpenDocument Text format
    Odt {
        /// The theme which should be used for the rendered document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        theme: Option<Theme>,
    },

    /// Markdown
    Markdown {
        /// The theme which should be used for the rendered document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        theme: Option<Theme>,
    },

    /// CommonMark flavored Markdown
    Commonmark {
        /// The theme which should be used for the rendered document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        theme: Option<Theme>,
    },

    /// CommonMark flavored Markdown with pandoc extensions
    CommonmarkX {
        /// The theme which should be used for the rendered document
        #[serde(default, skip_serializing_if = "crate::utils::is_default")]
        theme: Option<Theme>,
    },
}

impl OutputFormat {
    /// Create the PDF output format with the default configuration.
    pub fn default_pdf() -> Self {
        Self::Pdf {
            engine: Default::default(),
            theme: Default::default(),
        }
    }
}

impl Default for OutputFormat {
    fn default() -> Self {
        Self::default_pdf()
    }
}

impl OutputFormat {
    /// The color theme of the output document.
    pub fn theme(&self) -> Option<&str> {
        match self {
            Self::Pdf { theme, .. }
            | Self::Docx { theme }
            | Self::Odt { theme }
            | Self::Markdown { theme }
            | Self::Commonmark { theme }
            | Self::CommonmarkX { theme } => theme.as_deref(),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
pub struct Theme(String);

impl Theme {
    pub fn new(theme: String) -> Result<Self, &'static str> {
        if !theme
            .chars()
            .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
        {
            return Err("Only alphanumeric chars and `-_` are allowed");
        }

        Ok(Self(theme))
    }
    pub fn inner(&self) -> &str {
        &self.0
    }

    pub fn into_inner(self) -> String {
        self.0
    }
}

impl<'de> Deserialize<'de> for Theme {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        let inner = String::deserialize(deserializer)?;

        // Return the actual contract
        Self::new(inner).map_err(D::Error::custom)
    }
}

impl Deref for Theme {
    type Target = str;

    fn deref(&self) -> &Self::Target {
        self.0.as_str()
    }
}

impl TryFrom<String> for Theme {
    type Error = &'static str;

    fn try_from(value: String) -> Result<Self, Self::Error> {
        Self::new(value)
    }
}

/// Specifies the program that is used to render the PDF document from the source template or an
/// intermediary format.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
#[serde(rename_all = "snake_case")]
pub enum PdfEngine {
    /// Use latex as a PDF rendering engine
    #[default]
    Latex,

    /// Use LibreOffice as a PDFs rendering engine
    LibreOffice,
}

#[cfg(test)]
mod tests {
    use pretty_assertions::assert_eq;
    use serde_json::json;
    use strum::VariantNames;

    use super::*;

    #[test]
    fn default_value() {
        assert_eq!(
            OutputFormat::Pdf {
                engine: Default::default(),
                theme: Default::default(),
            },
            OutputFormat::default()
        );
    }

    #[test]
    fn serialize_strum_variant_names() {
        assert_eq!(
            "pdf",
            OutputFormat::Pdf {
                engine: Default::default(),
                theme: Default::default(),
            }
            .as_ref()
        );
        assert_eq!(
            "docx",
            OutputFormat::Docx {
                theme: Default::default(),
            }
            .as_ref()
        );
        assert_eq!(
            "odt",
            OutputFormat::Odt {
                theme: Default::default(),
            }
            .as_ref()
        );
        assert_eq!(
            "markdown",
            OutputFormat::Markdown {
                theme: Default::default(),
            }
            .as_ref()
        );
        assert_eq!(
            "commonmark",
            OutputFormat::Commonmark {
                theme: Default::default(),
            }
            .as_ref()
        );
        assert_eq!(
            "commonmark_x",
            OutputFormat::CommonmarkX {
                theme: Default::default(),
            }
            .as_ref()
        );
    }

    #[test]
    fn iterate_strum_variant_names() {
        assert_eq!(
            [
                "pdf",
                "docx",
                "odt",
                "markdown",
                "commonmark",
                "commonmark_x",
            ],
            OutputFormat::VARIANTS
        );
    }

    #[test]
    fn serialize_json() {
        assert_eq!(
            json!({
                "format": "pdf",
            }),
            serde_json::to_value(OutputFormat::Pdf {
                engine: Default::default(),
                theme: Default::default(),
            })
            .unwrap()
        );
        assert_eq!(
            json!({
            "format": "docx",
            }),
            serde_json::to_value(OutputFormat::Docx {
                theme: Default::default(),
            })
            .unwrap()
        );
        assert_eq!(
            json!({
            "format": "odt",
            }),
            serde_json::to_value(OutputFormat::Odt {
                theme: Default::default(),
            })
            .unwrap()
        );
        assert_eq!(
            json!({
            "format": "markdown",
            }),
            serde_json::to_value(OutputFormat::Markdown {
                theme: Default::default(),
            })
            .unwrap()
        );
        assert_eq!(
            json!({
            "format": "commonmark",
            }),
            serde_json::to_value(OutputFormat::Commonmark {
                theme: Default::default(),
            })
            .unwrap()
        );
        assert_eq!(
            json!({
            "format": "commonmark_x",
            }),
            serde_json::to_value(OutputFormat::CommonmarkX {
                theme: Default::default(),
            })
            .unwrap()
        );
    }

    #[test]
    fn deserialize_json() {
        assert_eq!(
            OutputFormat::Pdf {
                engine: Default::default(),
                theme: Default::default(),
            },
            serde_json::from_value(json!({"format": "pdf"})).unwrap()
        );
        assert_eq!(
            OutputFormat::Docx {
                theme: Default::default(),
            },
            serde_json::from_value(json!({"format": "docx"})).unwrap()
        );
        assert_eq!(
            OutputFormat::Odt {
                theme: Default::default(),
            },
            serde_json::from_value(json!({"format": "odt"})).unwrap()
        );
        assert_eq!(
            OutputFormat::Markdown {
                theme: Default::default(),
            },
            serde_json::from_value(json!({"format": "markdown"})).unwrap()
        );
        assert_eq!(
            OutputFormat::Commonmark {
                theme: Default::default(),
            },
            serde_json::from_value(json!({"format": "commonmark"})).unwrap()
        );
        assert_eq!(
            OutputFormat::CommonmarkX {
                theme: Default::default(),
            },
            serde_json::from_value(json!({"format": "commonmark_x"})).unwrap()
        );

        // Invalid theme
        assert!(serde_json::from_value::<OutputFormat>(
            json!({"format": "commonmark_x", "theme": "/asd/"})
        )
        .is_err());
    }

    #[test]
    fn theme_invalid() {
        assert!(Theme::try_from("value".to_string()).is_ok());
        assert!(Theme::try_from("/".to_string()).is_err());
        assert!(Theme::try_from("..".to_string()).is_err());
    }
}