mod gemini;
mod gopher;
mod raw;

use crate::template::{Context, Value};
use std::collections::HashMap;
use std::fs::read_dir;
use std::io::{Error, Result};
use std::path::{Path, PathBuf};
use time::{OffsetDateTime, format_description::FormatItem, macros::format_description};

const DATE_FORMAT: &[FormatItem<'_>] = format_description!("[year]-[month]-[day]");

struct ArchiveEntry {
    id: String,
    slug: String,
}

type Archiver = fn(&Path, &Path, &Path, &Context) -> Result<()>;

impl ArchiveEntry {
    pub fn to_template_context(archive_entries: &[ArchiveEntry]) -> Result<Context> {
        let mut context = HashMap::new();

        let archive_entries_collection = archive_entries
            .iter()
            .map(ArchiveEntry::to_template_value)
            .collect();

        let archive_length: u64 = archive_entries
            .len()
            .try_into()
            .map_err(|_| Error::other("Too many items in the archive."))?;
        context.insert(
            "archive_length".to_string(),
            Value::Unsigned(archive_length),
        );
        context.insert(
            "posts".to_string(),
            Value::Collection(archive_entries_collection),
        );

        Ok(context)
    }

    pub fn to_template_value(&self) -> Context {
        let mut context = HashMap::new();

        context.insert("id".to_string(), Value::String(self.id.clone()));

        context.insert("slug".to_string(), Value::String(self.slug.clone()));

        if let Some(title) = self.title() {
            context.insert("title".to_string(), Value::String(title));
        }

        context
    }

    fn title(&self) -> Option<String> {
        let date = OffsetDateTime::from_unix_timestamp_nanos(
            (self.id.parse::<u64>().ok()? * 1_000_000).into(),
        )
        .ok()?;
        let short_date = date.format(&DATE_FORMAT).ok()?;
        let title = self.slug.replace('-', " ");
        Some(format!("{short_date} {title}"))
    }
}

fn read_archive(archive_directory: &PathBuf) -> Vec<ArchiveEntry> {
    let mut archive_entries = Vec::new();
    if let Ok(entries) = read_dir(archive_directory) {
        for entry in entries.filter_map(Result::ok) {
            let entry_path = entry.path();
            let post_id = entry.file_name();
            if let Ok(entry_type) = entry.file_type()
                && entry_type.is_dir()
                && let Ok(candidates) = read_dir(&entry_path)
            {
                for candidate in candidates.filter_map(Result::ok) {
                    let candidate_path = candidate.path();
                    if let Some(extension) = candidate_path.extension()
                        && extension == "gmi"
                        && let Some(slug) = candidate_path.file_stem()
                        && let (Some(post_id), Some(slug)) = (post_id.to_str(), slug.to_str())
                    {
                        archive_entries.push(ArchiveEntry {
                            id: post_id.to_string(),
                            slug: slug.to_string(),
                        });
                    }
                }
            }
        }
    }

    archive_entries.sort_by(|a, b| b.id.cmp(&a.id));
    archive_entries
}

pub fn archive(
    archive_directory: &PathBuf,
    template_directory: &Path,
    output_directory: &Path,
) -> Result<()> {
    let archivers = available_archivers();
    let archive_entries = read_archive(archive_directory);
    let context = ArchiveEntry::to_template_context(&archive_entries)?;
    for archiver in archivers {
        archiver(
            archive_directory,
            template_directory,
            output_directory,
            &context,
        )?;
    }
    Ok(())
}

fn available_archivers() -> Vec<Archiver> {
    vec![raw::archive, gemini::archive, gopher::archive]
}

#[cfg(test)]
mod tests {
    use std::fs::create_dir_all;

    use super::*;
    use crate::template::Value;

    use test_utilities::*;

    // Archive template values

    #[test]
    fn test_creates_context_with_empty_archive_entries() {
        if let Ok(context) = ArchiveEntry::to_template_context(&[]) {
            assert_eq!(context.get("archive_length"), Some(&Value::Unsigned(0)));
            if let Some(Value::Collection(posts)) = &context.get("posts") {
                assert!(posts.is_empty());
            } else {
                panic!("The posts context was not the right type.");
            }
        } else {
            panic!("Could not generate template context.");
        }
    }

    #[test]
    fn test_creates_context_with_post_slice() {
        let archive_entry = ArchiveEntry {
            id: "you-know-what-is-cool".to_string(),
            slug: "the-archiving-shelves-with-a-spinning-lever-to-move-them".to_string(),
        };

        if let Ok(context) = ArchiveEntry::to_template_context(&[archive_entry]) {
            assert_eq!(context.get("archive_length"), Some(&Value::Unsigned(1)));
            if let Some(Value::Collection(posts)) = &context.get("posts") {
                if let Some(post) = posts.first() {
                    assert_eq!(
                        post["id"],
                        Value::String("you-know-what-is-cool".to_string())
                    );
                } else {
                    panic!("The template context had no posts");
                }
            } else {
                panic!("The posts context was not the right type.");
            }
        } else {
            panic!("Could not generate context");
        }
    }

    #[test]
    fn test_converts_archive_entry_without_title_to_context() {
        let archive_entry = ArchiveEntry {
            id: "they-always-show-them-in-spy-films".to_string(),
            slug: "or-like-universities".to_string(),
        };

        let context = archive_entry.to_template_value();

        assert_eq!(
            context.get("id"),
            Some(&Value::String(
                "they-always-show-them-in-spy-films".to_string()
            ))
        );
        assert_eq!(
            context.get("slug"),
            Some(&Value::String("or-like-universities".to_string()))
        );
        assert!(!context.contains_key("title"));
    }

    #[test]
    fn test_converts_archive_entry_with_title_to_context() {
        let archive_entry = ArchiveEntry {
            id: "1736035200000".to_string(),
            slug: "need-a-warehouse".to_string(),
        };

        let context = archive_entry.to_template_value();

        assert_eq!(
            context.get("id"),
            Some(&Value::String("1736035200000".to_string()))
        );
        assert_eq!(
            context.get("slug"),
            Some(&Value::String("need-a-warehouse".to_string()))
        );
        assert_eq!(
            context.get("title"),
            Some(&Value::String("2025-01-05 need a warehouse".to_string()))
        );
    }

    // Archive Finder
    #[test]
    fn test_finds() {
        let test_dir = setup_test_dir();
        let archive_dir = test_dir.join("archive");
        let template_dir = test_dir.join("templates");
        let output_dir = test_dir.join("output");

        let first_post_dir = archive_dir.join("1736035200000");
        create_dir_all(&first_post_dir).expect("Could not first create post test directory");
        create_test_file(
            &first_post_dir.join("my-very-cool-post.gmi"),
            "is full of flowers",
        );

        let second_post_dir = archive_dir.join("1736121600000");
        create_dir_all(&second_post_dir).expect("Could not create second post test directory");
        create_test_file(
            &second_post_dir.join("my-very-sad-post.gmi"),
            "is full of regrets",
        );

        let bad_file_dir = archive_dir.join("1736121600001");
        create_dir_all(&bad_file_dir).expect("Could not create bad file test directory");
        create_test_file(&bad_file_dir.join("my-very-bad-file"), "is full of lies");

        create_dir_all(&template_dir).expect("Could not create template test directory");
        create_dir_all(&output_dir).expect("Could not create output test directory");

        archive(&archive_dir, &template_dir, &output_dir).expect("Archive failed");

        assert_file_contains(
            &output_dir.join("index.gmi"),
            "\n=> ./1736035200000/my-very-cool-post.gmi 2025-01-05 my very cool post",
        );
        assert_file_contains(
            &output_dir.join("index.gmi"),
            "\n=> ./1736121600000/my-very-sad-post.gmi 2025-01-06 my very sad post",
        );
        assert_file_contents(
            &output_dir.join("1736035200000/my-very-cool-post.gmi"),
            "is full of flowers",
        );
        assert_file_contents(
            &output_dir.join("1736121600000/my-very-sad-post.gmi"),
            "is full of regrets",
        );
        assert!(&output_dir.join("1736121600001/my-very-bad-file").exists());
        assert_file_does_not_contain(
            &output_dir.join("index.gmi"),
            "1736121600001/my-very-bad-file",
        );
        cleanup_test_dir(&test_dir);
    }
}