//! Official JP download inventory extraction.

use super::yostar_jp::{verified_official_platforms, PatchPlatform, YostarJpResourceRoot};
use std::collections::{BTreeMap, BTreeSet, HashSet};

/// Download inventory extracted from the official JP catalog bytes.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct YostarJpDownloadInventory {
    /// Patch-pack zip names from `BundlePackingInfo.bytes`.
    pub bundle_patch_pack_names: Vec<String>,
    /// Table file names from `TableCatalog.bytes`.
    pub table_file_names: Vec<String>,
    /// Media file relative paths from `MediaCatalog.bytes`.
    pub media_file_names: Vec<String>,
}

/// Platform-specific catalog inventory extracted from official JP bytes.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct YostarJpPlatformCatalogInventory {
    /// Platform this inventory belongs to.
    pub platform: PatchPlatform,
    /// Patch-pack zip names from this platform's `BundlePackingInfo.bytes`.
    pub bundle_patch_pack_names: Vec<String>,
    /// Media file relative paths from this platform's `MediaCatalog.bytes`.
    pub media_file_names: Vec<String>,
}

impl YostarJpPlatformCatalogInventory {
    /// Extracts one platform inventory from official JP catalog bytes.
    pub fn from_catalog_bytes(
        platform: PatchPlatform,
        bundle_packing_info: &[u8],
        media_catalog: &[u8],
    ) -> Self {
        Self {
            platform,
            bundle_patch_pack_names: extract_full_patch_pack_names(bundle_packing_info),
            media_file_names: extract_media_file_paths(media_catalog),
        }
    }

    /// Returns this platform's official bundle patch-pack URLs.
    pub fn bundle_patch_pack_urls(
        &self,
        root: &YostarJpResourceRoot,
    ) -> Result<Vec<String>, String> {
        self.bundle_patch_pack_names
            .iter()
            .map(|name| root.bundle_patch_pack(self.platform, name))
            .collect()
    }

    /// Returns this platform's official media URLs.
    pub fn media_file_urls(&self, root: &YostarJpResourceRoot) -> Result<Vec<String>, String> {
        self.media_file_names
            .iter()
            .map(|name| root.media_file(self.platform, name))
            .collect()
    }
}

/// Multi-platform download inventory with shared table files and platform
/// specific patch-pack/media catalogs.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct YostarJpPlatformDownloadInventory {
    /// Table file names from the shared `TableCatalog.bytes`.
    pub table_file_names: Vec<String>,
    /// Per-platform bundle/media inventories.
    pub platform_catalogs: Vec<YostarJpPlatformCatalogInventory>,
}

impl YostarJpPlatformDownloadInventory {
    /// Extracts a multi-platform inventory from official JP catalog bytes.
    pub fn from_catalog_bytes(
        table_catalog: &[u8],
        platform_catalogs: Vec<YostarJpPlatformCatalogInventory>,
    ) -> Self {
        Self {
            table_file_names: extract_table_file_names(table_catalog),
            platform_catalogs: merge_platform_catalogs(platform_catalogs),
        }
    }

    /// Builds a platform inventory by reusing a legacy shared inventory for
    /// each requested platform.
    pub fn from_shared_inventory(
        inventory: YostarJpDownloadInventory,
        platforms: &[PatchPlatform],
    ) -> Self {
        let platform_catalogs = unique_platforms(platforms)
            .into_iter()
            .map(|platform| YostarJpPlatformCatalogInventory {
                platform,
                bundle_patch_pack_names: inventory.bundle_patch_pack_names.clone(),
                media_file_names: inventory.media_file_names.clone(),
            })
            .collect();

        Self {
            table_file_names: inventory.table_file_names,
            platform_catalogs,
        }
    }

    /// Returns the official table file URLs.
    pub fn table_file_urls(&self, root: &YostarJpResourceRoot) -> Result<Vec<String>, String> {
        self.table_file_names
            .iter()
            .map(|name| root.table_bundle(name))
            .collect()
    }

    /// Returns the complete direct-download URL set for multiple platforms.
    ///
    /// Table bundles are emitted once. Patch-pack and media files are emitted
    /// from the matching platform catalog only, which avoids creating invalid
    /// cross-platform URL combinations.
    pub fn direct_download_urls_for_platforms(
        &self,
        root: &YostarJpResourceRoot,
        platforms: &[PatchPlatform],
    ) -> Result<Vec<String>, String> {
        let mut urls = Vec::new();
        let mut seen = HashSet::new();

        append_unique_urls(&mut urls, &mut seen, self.table_file_urls(root)?);

        for platform in unique_platforms(platforms) {
            let catalog = self.platform_catalog(platform).ok_or_else(|| {
                format!(
                    "Missing official catalog inventory for platform: {}",
                    platform.as_str()
                )
            })?;

            append_unique_urls(&mut urls, &mut seen, catalog.bundle_patch_pack_urls(root)?);
            append_unique_urls(&mut urls, &mut seen, catalog.media_file_urls(root)?);
        }

        Ok(urls)
    }

    /// Returns the complete direct-download URL set for all verified official
    /// JP platforms.
    pub fn direct_download_urls_for_verified_platforms(
        &self,
        root: &YostarJpResourceRoot,
    ) -> Result<Vec<String>, String> {
        self.direct_download_urls_for_platforms(root, &verified_official_platforms())
    }

    fn platform_catalog(
        &self,
        platform: PatchPlatform,
    ) -> Option<&YostarJpPlatformCatalogInventory> {
        self.platform_catalogs
            .iter()
            .find(|catalog| catalog.platform == platform)
    }
}

impl YostarJpDownloadInventory {
    /// Extracts an inventory from the three official JP catalog bytes.
    pub fn from_catalog_bytes(
        bundle_packing_info: &[u8],
        table_catalog: &[u8],
        media_catalog: &[u8],
    ) -> Self {
        Self {
            bundle_patch_pack_names: extract_full_patch_pack_names(bundle_packing_info),
            table_file_names: extract_table_file_names(table_catalog),
            media_file_names: extract_media_file_paths(media_catalog),
        }
    }

    /// Returns the official bundle patch-pack URLs for a platform.
    pub fn bundle_patch_pack_urls(
        &self,
        root: &YostarJpResourceRoot,
        platform: PatchPlatform,
    ) -> Result<Vec<String>, String> {
        self.bundle_patch_pack_names
            .iter()
            .map(|name| root.bundle_patch_pack(platform, name))
            .collect()
    }

    /// Returns the official table file URLs.
    pub fn table_file_urls(&self, root: &YostarJpResourceRoot) -> Result<Vec<String>, String> {
        self.table_file_names
            .iter()
            .map(|name| root.table_bundle(name))
            .collect()
    }

    /// Returns the official media file URLs for a platform.
    pub fn media_file_urls(
        &self,
        root: &YostarJpResourceRoot,
        platform: PatchPlatform,
    ) -> Result<Vec<String>, String> {
        self.media_file_names
            .iter()
            .map(|name| root.media_file(platform, name))
            .collect()
    }

    /// Returns the complete direct-download URL set for a platform.
    pub fn direct_download_urls(
        &self,
        root: &YostarJpResourceRoot,
        platform: PatchPlatform,
    ) -> Result<Vec<String>, String> {
        let mut urls = self.bundle_patch_pack_urls(root, platform)?;
        urls.extend(self.table_file_urls(root)?);
        urls.extend(self.media_file_urls(root, platform)?);
        Ok(urls)
    }

    /// Returns the complete direct-download URL set for multiple platforms.
    ///
    /// Table bundles are emitted once. Platform-specific URLs are emitted in
    /// platform order and deduplicated by URL so shared Android media paths
    /// only appear once.
    pub fn direct_download_urls_for_platforms(
        &self,
        root: &YostarJpResourceRoot,
        platforms: &[PatchPlatform],
    ) -> Result<Vec<String>, String> {
        let mut urls = Vec::new();
        let mut seen = HashSet::new();

        append_unique_urls(&mut urls, &mut seen, self.table_file_urls(root)?);

        for platform in unique_platforms(platforms) {
            append_unique_urls(
                &mut urls,
                &mut seen,
                self.bundle_patch_pack_urls(root, platform)?,
            );
            append_unique_urls(&mut urls, &mut seen, self.media_file_urls(root, platform)?);
        }

        Ok(urls)
    }

    /// Returns the complete direct-download URL set for all verified official
    /// JP platforms.
    pub fn direct_download_urls_for_verified_platforms(
        &self,
        root: &YostarJpResourceRoot,
    ) -> Result<Vec<String>, String> {
        self.direct_download_urls_for_platforms(root, &verified_official_platforms())
    }
}

fn merge_platform_catalogs(
    catalogs: Vec<YostarJpPlatformCatalogInventory>,
) -> Vec<YostarJpPlatformCatalogInventory> {
    let mut merged = Vec::<YostarJpPlatformCatalogInventory>::new();

    for catalog in catalogs {
        if let Some(existing) = merged
            .iter_mut()
            .find(|existing| existing.platform == catalog.platform)
        {
            merge_names(
                &mut existing.bundle_patch_pack_names,
                catalog.bundle_patch_pack_names,
            );
            merge_names(&mut existing.media_file_names, catalog.media_file_names);
        } else {
            merged.push(catalog);
        }
    }

    merged.sort_by_key(|catalog| catalog.platform);
    merged
}

fn merge_names(existing: &mut Vec<String>, names: Vec<String>) {
    let mut merged = existing.iter().cloned().collect::<BTreeSet<_>>();
    merged.extend(names);
    *existing = merged.into_iter().collect();
}

fn extract_full_patch_pack_names(data: &[u8]) -> Vec<String> {
    extract_file_names(data, &["zip"]) // only .zip names survive here
        .into_iter()
        .filter(|name| is_full_patch_pack_name(name))
        .collect()
}

fn extract_table_file_names(data: &[u8]) -> Vec<String> {
    let mut counts = BTreeMap::<String, usize>::new();

    // Real TableCatalog bytes list top-level downloadable table files twice,
    // while package-internal stage/resource .zip names normally appear once
    // next to rawdata paths and are not direct TableBundles URLs.
    for string in extract_printable_strings(data, 4) {
        for name in candidate_file_names(&string, &["db", "zip"]) {
            *counts.entry(name).or_default() += 1;
        }
    }

    counts
        .into_iter()
        .filter_map(|(name, count)| (count >= 2).then_some(name))
        .collect()
}

fn extract_file_names(data: &[u8], extensions: &[&str]) -> Vec<String> {
    let mut names = BTreeSet::new();

    for string in extract_printable_strings(data, 4) {
        for name in candidate_file_names(&string, extensions) {
            names.insert(name);
        }
    }

    names.into_iter().collect()
}

fn extract_media_file_paths(data: &[u8]) -> Vec<String> {
    let mut paths = BTreeSet::new();

    for string in extract_printable_strings(data, 4) {
        for path in
            candidate_relative_paths(&string, &["zip", "mp4", "png", "jpg", "jpeg", "ogg", "wav"])
        {
            paths.insert(path);
        }
    }

    paths.into_iter().collect()
}

fn extract_printable_strings(data: &[u8], min_len: usize) -> Vec<String> {
    let mut strings = Vec::new();
    let mut current = Vec::new();

    for &byte in data {
        if byte.is_ascii_graphic() || byte == b' ' {
            current.push(byte);
        } else if current.len() >= min_len {
            strings.push(String::from_utf8_lossy(&current).into_owned());
            current.clear();
        } else {
            current.clear();
        }
    }

    if current.len() >= min_len {
        strings.push(String::from_utf8_lossy(&current).into_owned());
    }

    strings
}

fn candidate_file_names(value: &str, extensions: &[&str]) -> Vec<String> {
    let mut names = Vec::new();
    let bytes = value.as_bytes();

    for extension in extensions {
        let suffix = format!(".{extension}");
        let mut search_from = 0;

        while let Some(relative_index) = value[search_from..].find(&suffix) {
            let extension_start = search_from + relative_index;
            let start = filename_start(bytes, extension_start);
            let end = extension_start + suffix.len();
            let candidate = &value[start..end];
            let candidate = candidate.rsplit(['/', '\\']).next().unwrap_or(candidate);

            if is_plausible_file_name(candidate) {
                names.push(candidate.to_string());
            }

            search_from = end;
        }
    }

    names
}

fn candidate_relative_paths(value: &str, extensions: &[&str]) -> Vec<String> {
    let mut paths = Vec::new();
    let bytes = value.as_bytes();

    for extension in extensions {
        let suffix = format!(".{extension}");
        let mut search_from = 0;

        while let Some(relative_index) = value[search_from..].find(&suffix) {
            let extension_start = search_from + relative_index;
            let start = filename_start(bytes, extension_start);
            let end = extension_start + suffix.len();
            let candidate = &value[start..end];
            let candidate = candidate.replace('\\', "/");

            if is_plausible_relative_path(&candidate) {
                paths.push(candidate);
            }

            search_from = end;
        }
    }

    paths
}

fn filename_start(bytes: &[u8], mut index: usize) -> usize {
    while index > 0 {
        let byte = bytes[index - 1];
        if byte.is_ascii_alphanumeric() || matches!(byte, b'_' | b'-' | b'.' | b'/' | b'\\') {
            index -= 1;
        } else {
            break;
        }
    }

    index
}

fn is_full_patch_pack_name(name: &str) -> bool {
    let bytes = name.as_bytes();
    if bytes.len() != 17 || !name.starts_with("FullPatch_") || !name.ends_with(".zip") {
        return false;
    }

    bytes[10..13].iter().all(|byte| byte.is_ascii_digit())
}

fn is_plausible_file_name(name: &str) -> bool {
    !name.is_empty()
        && !name.contains('/')
        && !name.contains('\\')
        && !name.contains("..")
        && !name.contains(':')
        && !name.contains('=')
        && name
            .chars()
            .all(|ch| ch.is_ascii_alphanumeric() || matches!(ch, '_' | '-' | '.'))
}

fn is_plausible_relative_path(path: &str) -> bool {
    if path.is_empty()
        || path.starts_with('/')
        || path.starts_with('.')
        || path.contains("..")
        || path.contains(':')
        || path.contains('=')
        || !path.contains('/')
    {
        return false;
    }

    path.split('/').all(|segment| {
        !segment.is_empty()
            && segment != "."
            && segment != ".."
            && segment
                .chars()
                .all(|ch| ch.is_ascii_alphanumeric() || matches!(ch, '_' | '-' | '.'))
    })
}

fn unique_platforms(platforms: &[PatchPlatform]) -> Vec<PatchPlatform> {
    platforms
        .iter()
        .copied()
        .fold(Vec::new(), |mut unique, platform| {
            if !unique.contains(&platform) {
                unique.push(platform);
            }
            unique
        })
}

fn append_unique_urls(urls: &mut Vec<String>, seen: &mut HashSet<String>, next_urls: Vec<String>) {
    for url in next_urls {
        if seen.insert(url.clone()) {
            urls.push(url);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::official::yostar_jp::YostarJpResourceRoot;

    const ROOT: &str = "r93_dctuo3tcd029wwxnvb55";

    #[test]
    fn extracts_download_names_from_synthetic_bytes() {
        let inventory = YostarJpDownloadInventory::from_catalog_bytes(
            b"prefix FullPatch_000.zip noise FullPatch_114.zip suffix",
            b"GameData\\Table\\ExcelDB.db\0ExcelDB.db\0rawdata/table/excel/ignored.bytes\0Battle.zip\0Battle.zip8",
            b"audio/voc_jp/jp_airi/jp_airi\0GameData\\Audio\\VOC_JP\\JP_Airi.zip8\0audio/voc_jp/jp_akane/jp_akane\0GameData\\Audio\\VOC_JP\\JP_Akane.zip",
        );

        assert_eq!(
            inventory.bundle_patch_pack_names,
            vec![
                "FullPatch_000.zip".to_string(),
                "FullPatch_114.zip".to_string()
            ]
        );
        assert_eq!(
            inventory.table_file_names,
            vec!["Battle.zip".to_string(), "ExcelDB.db".to_string(),]
        );
        assert_eq!(
            inventory.media_file_names,
            vec![
                "GameData/Audio/VOC_JP/JP_Airi.zip".to_string(),
                "GameData/Audio/VOC_JP/JP_Akane.zip".to_string(),
            ]
        );
    }

    #[test]
    fn extracts_only_top_level_table_files_from_table_catalog() {
        let inventory = YostarJpPlatformDownloadInventory::from_catalog_bytes(
            b"ExcelDB.db\0ExcelDB.db\0TablePatchPack_Prologue_GroundStage_1.zip\0TablePatchPack_Prologue_GroundStage_1.zip|1011101_01_s1_01_mainstreet_p01_d.zip\0rawdata/ground/stage/bytes/1011101_01_s1_01_mainstreet_p01_d.bytes",
            Vec::new(),
        );

        assert_eq!(
            inventory.table_file_names,
            vec![
                "ExcelDB.db".to_string(),
                "TablePatchPack_Prologue_GroundStage_1.zip".to_string()
            ]
        );
    }

    #[test]
    fn builds_direct_download_urls() {
        let inventory = YostarJpDownloadInventory::from_catalog_bytes(
            b"FullPatch_000.zip FullPatch_001.zip",
            b"ExcelDB.db ExcelDB.db Battle.zip Battle.zip",
            b"GameData\\Audio\\VOC_JP\\JP_Airi.zip GameData\\Audio\\VOC_JP\\JP_Akane.zip",
        );
        let root = YostarJpResourceRoot::from_root_token(ROOT).unwrap();

        let urls = inventory
            .direct_download_urls(&root, PatchPlatform::Windows)
            .unwrap();

        assert_eq!(urls[0], "https://prod-clientpatch.bluearchiveyostar.com/r93_dctuo3tcd029wwxnvb55/Windows_PatchPack/FullPatch_000.zip");
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/TableBundles/ExcelDB.db")));
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/MediaResources-Windows/GameData/Audio/VOC_JP/JP_Airi.zip")));
    }

    #[test]
    fn builds_direct_download_urls_for_verified_platforms() {
        let inventory = YostarJpDownloadInventory::from_catalog_bytes(
            b"FullPatch_000.zip",
            b"ExcelDB.db ExcelDB.db",
            b"GameData\\Audio\\VOC_JP\\JP_Airi.zip",
        );
        let root = YostarJpResourceRoot::from_root_token(ROOT).unwrap();

        let urls = inventory
            .direct_download_urls_for_verified_platforms(&root)
            .unwrap();

        assert_eq!(urls.len(), 5);
        assert!(urls
            .iter()
            .any(|url| url.contains("/Windows_PatchPack/FullPatch_000.zip")));
        assert!(urls
            .iter()
            .any(|url| url.contains("/Android_PatchPack/FullPatch_000.zip")));
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/TableBundles/ExcelDB.db")));
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/MediaResources-Windows/GameData/Audio/VOC_JP/JP_Airi.zip")));
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/MediaResources/GameData/Audio/VOC_JP/JP_Airi.zip")));
    }

    #[test]
    fn builds_platform_specific_download_urls_without_cross_mixing_catalogs() {
        let inventory = YostarJpPlatformDownloadInventory::from_catalog_bytes(
            b"ExcelDB.db ExcelDB.db",
            vec![
                YostarJpPlatformCatalogInventory::from_catalog_bytes(
                    PatchPlatform::Windows,
                    b"FullPatch_000.zip",
                    b"GameData\\Audio\\VOC_JP\\JP_Airi_Win.zip",
                ),
                YostarJpPlatformCatalogInventory::from_catalog_bytes(
                    PatchPlatform::Android,
                    b"FullPatch_001.zip",
                    b"GameData\\Audio\\VOC_JP\\JP_Airi_Android.zip",
                ),
            ],
        );
        let root = YostarJpResourceRoot::from_root_token(ROOT).unwrap();

        let urls = inventory
            .direct_download_urls_for_verified_platforms(&root)
            .unwrap();

        assert!(urls
            .iter()
            .any(|url| url.ends_with("/Windows_PatchPack/FullPatch_000.zip")));
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/Android_PatchPack/FullPatch_001.zip")));
        assert!(urls
            .iter()
            .any(|url| url
                .ends_with("/MediaResources-Windows/GameData/Audio/VOC_JP/JP_Airi_Win.zip")));
        assert!(urls
            .iter()
            .any(|url| url.ends_with("/MediaResources/GameData/Audio/VOC_JP/JP_Airi_Android.zip")));
        assert!(!urls
            .iter()
            .any(|url| url.ends_with("/Android_PatchPack/FullPatch_000.zip")));
        assert!(!urls
            .iter()
            .any(|url| url.ends_with("/Windows_PatchPack/FullPatch_001.zip")));
    }

    #[test]
    fn media_catalog_uses_download_relative_path_not_leaf_name() {
        let inventory = YostarJpPlatformDownloadInventory::from_catalog_bytes(
            b"ExcelDB.db ExcelDB.db",
            vec![YostarJpPlatformCatalogInventory::from_catalog_bytes(
                PatchPlatform::Windows,
                b"FullPatch_000.zip",
                b"scenario/event/10000_title_sound\0Prologue\\Scenario\\Event\\10000_Title_Sound.ogg\0 10000_Title_Sound.ogg",
            )],
        );
        let root = YostarJpResourceRoot::from_root_token(ROOT).unwrap();

        let urls = inventory
            .direct_download_urls_for_platforms(&root, &[PatchPlatform::Windows])
            .unwrap();

        assert!(urls.iter().any(|url| {
            url.ends_with("/MediaResources-Windows/Prologue/Scenario/Event/10000_Title_Sound.ogg")
        }));
        assert!(!urls
            .iter()
            .any(|url| url.ends_with("/MediaResources-Windows/10000_Title_Sound.ogg")));
    }

    #[test]
    #[ignore = "requires BAT_REAL_OFFICIAL_BUNDLE_PACKING_INFO, BAT_REAL_OFFICIAL_TABLE_CATALOG, BAT_REAL_OFFICIAL_MEDIA_CATALOG"]
    fn extracts_realistic_counts_from_official_shape() {
        let bundle_packing_info =
            std::fs::read(std::env::var("BAT_REAL_OFFICIAL_BUNDLE_PACKING_INFO").unwrap()).unwrap();
        let table_catalog =
            std::fs::read(std::env::var("BAT_REAL_OFFICIAL_TABLE_CATALOG").unwrap()).unwrap();
        let media_catalog =
            std::fs::read(std::env::var("BAT_REAL_OFFICIAL_MEDIA_CATALOG").unwrap()).unwrap();

        let inventory = YostarJpDownloadInventory::from_catalog_bytes(
            &bundle_packing_info,
            &table_catalog,
            &media_catalog,
        );

        assert_eq!(inventory.bundle_patch_pack_names.len(), 142);
        assert!(inventory.table_file_names.len() < 1000);
        assert!(inventory.media_file_names.len() >= 4000);
        assert!(inventory
            .bundle_patch_pack_names
            .iter()
            .any(|name| name == "FullPatch_000.zip"));
        assert!(inventory
            .table_file_names
            .iter()
            .any(|name| name == "ExcelDB.db"));
        assert!(inventory
            .media_file_names
            .iter()
            .any(|name| name == "GameData/Audio/VOC_JP/JP_Airi.zip"));
        assert!(inventory
            .media_file_names
            .iter()
            .any(|name| name.ends_with(".jpg")));
    }
}