use crate::State;
use crate::data::ModLoader;
use crate::install::{
    InstallPhaseDetails, InstallPhaseId, InstallProgress,
    InstallProgressReporter,
};
use crate::state::{
    AppliedContentSetPatch, CacheBehaviour, CachedEntry, ContentSourceKind,
    EditInstance, InstanceInstallStage, InstanceLink, SideType,
};
use crate::util::fetch::{
    DownloadMeta, DownloadReason, FetchProgressFn, fetch,
    fetch_advanced_with_progress, sha1_file_async, write_cached_icon,
};
use path_util::SafeRelativeUtf8UnixPathBuf;
use reqwest::Method;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::future::Future;

use std::path::PathBuf;
use std::pin::Pin;

#[derive(Serialize, Deserialize, Eq, PartialEq)]
#[serde(rename_all = "camelCase")]
pub struct PackFormat {
    pub game: String,
    pub format_version: i32,
    pub version_id: String,
    pub name: String,
    pub summary: Option<String>,
    pub files: Vec<PackFile>,
    pub dependencies: HashMap<PackDependency, String>,
}

#[derive(Serialize, Deserialize, Eq, PartialEq)]
#[serde(rename_all = "camelCase")]
pub struct PackFile {
    pub path: SafeRelativeUtf8UnixPathBuf,
    pub hashes: HashMap<PackFileHash, String>,
    pub env: Option<HashMap<EnvType, SideType>>,
    pub downloads: Vec<String>,
    pub file_size: u32,
}

#[derive(Serialize, Deserialize, Eq, PartialEq, Hash)]
#[serde(rename_all = "camelCase", from = "String")]
pub enum PackFileHash {
    Sha1,
    Sha512,
    Unknown(String),
}

impl From<String> for PackFileHash {
    fn from(s: String) -> Self {
        match s.as_str() {
            "sha1" => PackFileHash::Sha1,
            "sha512" => PackFileHash::Sha512,
            _ => PackFileHash::Unknown(s),
        }
    }
}

#[derive(Serialize, Deserialize, Eq, PartialEq, Hash)]
#[serde(rename_all = "camelCase")]
pub enum EnvType {
    Client,
    Server,
}

#[derive(Serialize, Deserialize, Clone, Copy, Hash, PartialEq, Eq, Debug)]
pub enum PackDependency {
    #[serde(rename = "forge")]
    Forge,

    #[serde(rename = "neoforge")]
    #[serde(alias = "neo-forge")]
    NeoForge,

    #[serde(rename = "fabric-loader")]
    FabricLoader,

    #[serde(rename = "quilt-loader")]
    QuiltLoader,

    #[serde(rename = "minecraft")]
    Minecraft,
}

#[derive(Serialize, Deserialize, Debug, Clone)]
#[serde(rename_all = "camelCase", tag = "type")]
pub enum CreatePackLocation {
    // Create a pack from a modrinth version ID (such as a modpack)
    FromVersionId {
        project_id: String,
        version_id: String,
        title: String,
        icon_url: Option<String>,
    },
    // Create a pack from a file (such as an .mrpack for installing from a file, or a folder name for importing)
    FromFile {
        path: PathBuf,
    },
}

#[derive(Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct CreatePackInstance {
    pub name: String, // the name of the instance and relative path
    pub game_version: String, // the game version of the instance
    pub modloader: ModLoader, // the modloader to use
    pub loader_version: Option<String>, // the modloader version to use, set to "latest", "stable", or the ID of your chosen loader. defaults to latest
    pub icon: Option<PathBuf>,          // the icon for the instance
    pub icon_url: Option<String>, // the URL icon for an instance during import
    pub link: Option<InstanceLink>,
    pub unknown_file: bool, // true when pack file isn't found on Modrinth via hash lookup
    pub skip_install_profile: Option<bool>,
    pub no_watch: Option<bool>,
}

// default
impl Default for CreatePackInstance {
    fn default() -> Self {
        CreatePackInstance {
            name: "Untitled".to_string(),
            game_version: "1.19.4".to_string(),
            modloader: ModLoader::Vanilla,
            loader_version: None,
            icon: None,
            icon_url: None,
            link: None,
            unknown_file: false,
            skip_install_profile: Some(true),
            no_watch: Some(false),
        }
    }
}

#[derive(Clone)]
pub enum CreatePackFile {
    Bytes(bytes::Bytes),
    // Local packs can be larger than available memory, so keep them file-backed.
    Path(PathBuf),
}

#[derive(Clone)]
pub struct CreatePack {
    pub file: CreatePackFile,
    pub description: CreatePackDescription,
}

// The hash lookup only gates the unknown-pack warning, so avoid a long blocking scan for huge local packs.
const MAX_LOCAL_FILE_HASH_LOOKUP_SIZE: u64 = 1024 * 1024 * 1024;

#[derive(Clone, Debug)]
pub struct CreatePackDescription {
    pub icon: Option<PathBuf>,
    pub override_title: Option<String>,
    pub project_id: Option<String>,
    pub version_id: Option<String>,
    pub instance_id: String,
    pub source_filename: Option<String>,
}

pub async fn get_instance_from_pack(
    location: CreatePackLocation,
) -> crate::Result<CreatePackInstance> {
    match location {
        CreatePackLocation::FromVersionId {
            project_id,
            version_id,
            title,
            icon_url,
        } => Ok(CreatePackInstance {
            name: title,
            icon_url,
            link: Some(InstanceLink::ModrinthModpack {
                project_id,
                version_id,
            }),
            ..Default::default()
        }),
        CreatePackLocation::FromFile { path } => {
            let file_name = path
                .file_stem()
                .unwrap_or_default()
                .to_string_lossy()
                .to_string();

            let is_known_file = if tokio::fs::metadata(&path).await?.len()
                <= MAX_LOCAL_FILE_HASH_LOOKUP_SIZE
            {
                let state = State::get().await?;
                let (_, hash) = sha1_file_async(&path).await?;
                match CachedEntry::get_file_many(
                    &[&hash],
                    Some(CacheBehaviour::StaleWhileRevalidateSkipOffline),
                    &state.pool,
                    &state.api_semaphore,
                )
                .await
                {
                    Ok(files) => !files.is_empty(),
                    Err(err) => {
                        tracing::warn!(
                            "Failed to check Modrinth file hash for {}: {}",
                            path.display(),
                            err
                        );
                        false
                    }
                }
            } else {
                false
            };

            Ok(CreatePackInstance {
                name: file_name,
                unknown_file: !is_known_file,
                ..Default::default()
            })
        }
    }
}

#[tracing::instrument(skip(reporter))]
#[allow(clippy::too_many_arguments)]
pub(crate) async fn generate_pack_from_version_id_with_reporter(
    project_id: String,
    version_id: String,
    title: String,
    icon_url: Option<String>,
    instance_id: String,
    reason: DownloadReason,
    reporter: InstallProgressReporter,
) -> crate::Result<CreatePack> {
    let state = State::get().await?;
    let has_icon_url = icon_url.is_some();

    let version = CachedEntry::get_version(
        &version_id,
        Some(CacheBehaviour::Bypass),
        &state.pool,
        &state.api_semaphore,
    )
    .await?
    .ok_or_else(|| {
        crate::ErrorKind::InputError(
            "Invalid version ID specified!".to_string(),
        )
    })?;

    // Update instance with correct loader and game version from the API version metadata,
    // so the UI shows accurate info while the pack file is still downloading.
    if let Some(game_version) = version.game_versions.first() {
        let loader = version
            .loaders
            .first()
            .map(|l| ModLoader::from_string(l))
            .unwrap_or(ModLoader::Vanilla);
        let game_version = game_version.clone();
        crate::api::instance::edit(
            &instance_id,
            EditInstance {
                content_set_patch: Some(AppliedContentSetPatch {
                    source_kind: None,
                    game_version: Some(game_version),
                    protocol_version: Some(None),
                    loader: Some(loader),
                    loader_version: None,
                }),
                ..EditInstance::default()
            },
        )
        .await?;
    }

    let (url, hash) =
        if let Some(file) = version.files.iter().find(|x| x.primary) {
            Some((file.url.clone(), file.hashes.get("sha1")))
        } else {
            version
                .files
                .first()
                .map(|file| (file.url.clone(), file.hashes.get("sha1")))
        }
        .ok_or_else(|| {
            crate::ErrorKind::InputError(
                "Specified version has no files".to_string(),
            )
        })?;

    let metadata =
        crate::api::instance::get(&instance_id)
            .await?
            .ok_or_else(|| {
                crate::ErrorKind::InputError(format!(
                    "Unknown instance {instance_id}"
                ))
            })?;

    let download_meta = DownloadMeta {
        reason,
        game_version: metadata.applied_content_set.game_version.clone(),
        loader: metadata.applied_content_set.loader.as_str().to_string(),
        dependent_on: Some(version_id.clone()),
    };

    let details = InstallPhaseDetails::Modpack {
        project_id: Some(project_id.clone()),
        version_id: Some(version_id.clone()),
        title: Some(title.clone()),
    };
    let mut last_reported_bytes = 0_u64;
    let mut progress =
        |current: u64,
         total: u64|
         -> Pin<Box<dyn Future<Output = crate::Result<()>> + Send>> {
            let min_delta = (total / 200).max(256 * 1024);
            if current < total
                && current.saturating_sub(last_reported_bytes) < min_delta
            {
                return Box::pin(async { Ok(()) });
            }

            last_reported_bytes = current;
            let reporter = reporter.clone();
            let details = details.clone();
            Box::pin(async move {
                reporter
                    .update(
                        InstallPhaseId::DownloadingPackFile,
                        Some(InstallProgress {
                            current,
                            total,
                            secondary: None,
                        }),
                        details,
                    )
                    .await?;
                Ok(())
            })
        };
    let progress = Some(&mut progress as &mut FetchProgressFn<'_>);

    let file = fetch_advanced_with_progress(
        Method::GET,
        &url,
        hash.map(|x| &**x),
        None,
        None,
        Some(&download_meta),
        None,
        None,
        &state.fetch_semaphore,
        &state.pool,
        progress,
    )
    .await?;

    let project = CachedEntry::get_project(
        &version.project_id,
        None,
        &state.pool,
        &state.api_semaphore,
    )
    .await?
    .ok_or_else(|| {
        crate::ErrorKind::InputError(
            "Invalid project ID specified!".to_string(),
        )
    })?;

    // Only fetch the pack icon when icon_url is provided (new profile).
    // When installing to an existing profile (e.g. server projects),
    // icon_url is None and we preserve the profile's existing icon.
    let icon = if has_icon_url {
        if let Some(icon_url) = project.icon_url {
            let state = State::get().await?;
            let icon_bytes = fetch(
                &icon_url,
                None,
                None,
                None,
                &state.fetch_semaphore,
                &state.pool,
            )
            .await?;

            let filename = icon_url.rsplit('/').next();

            if let Some(filename) = filename {
                Some(
                    write_cached_icon(
                        filename,
                        &state.directories.caches_dir(),
                        icon_bytes,
                        &state.io_semaphore,
                    )
                    .await?,
                )
            } else {
                None
            }
        } else {
            None
        }
    } else {
        None
    };

    // Set the icon immediately so the UI shows it during download.
    if let Some(ref icon_path) = icon {
        let _ = crate::api::instance::edit_icon(
            &instance_id,
            Some(icon_path.as_path()),
        )
        .await;
    }

    Ok(CreatePack {
        file: CreatePackFile::Bytes(file),
        description: CreatePackDescription {
            icon,
            override_title: Some(title),
            project_id: Some(project_id),
            version_id: Some(version_id),
            instance_id,
            source_filename: None,
        },
    })
}

#[tracing::instrument]

pub async fn generate_pack_from_file(
    path: PathBuf,
    instance_id: String,
) -> crate::Result<CreatePack> {
    let source_filename =
        path.file_name().map(|x| x.to_string_lossy().to_string());

    Ok(CreatePack {
        file: CreatePackFile::Path(path),
        description: CreatePackDescription {
            icon: None,
            override_title: None,
            project_id: None,
            version_id: None,
            instance_id,
            source_filename,
        },
    })
}

/// Sets generated instance attributes to the pack ones.
/// This includes the pack name, icon, game version, loader version, and loader
pub async fn set_instance_information(
    instance_id: String,
    description: &CreatePackDescription,
    backup_name: &str,
    pack_version_id: Option<&str>,
    dependencies: &HashMap<PackDependency, String>,
    _ignore_lock: bool,
) -> crate::Result<()> {
    let mut game_version: Option<&String> = None;
    let mut mod_loader = None;
    let mut loader_version = None;

    for (key, value) in dependencies {
        match key {
            PackDependency::Forge => {
                mod_loader = Some(ModLoader::Forge);
                loader_version = Some(value);
            }
            PackDependency::NeoForge => {
                mod_loader = Some(ModLoader::NeoForge);
                loader_version = Some(value);
            }
            PackDependency::FabricLoader => {
                mod_loader = Some(ModLoader::Fabric);
                loader_version = Some(value);
            }
            PackDependency::QuiltLoader => {
                mod_loader = Some(ModLoader::Quilt);
                loader_version = Some(value);
            }
            PackDependency::Minecraft => game_version = Some(value),
        }
    }

    let Some(game_version) = game_version else {
        return Err(crate::ErrorKind::InputError(
            "Pack did not specify Minecraft version".to_string(),
        )
        .into());
    };

    let mod_loader = mod_loader.unwrap_or(ModLoader::Vanilla);
    let loader_version = if mod_loader != ModLoader::Vanilla {
        crate::launcher::get_loader_version_from_profile(
            game_version,
            mod_loader,
            loader_version.cloned().as_deref(),
        )
        .await?
    } else {
        None
    };
    let link = match (&description.project_id, &description.version_id) {
        (Some(project_id), Some(version_id)) => {
            Some(InstanceLink::ModrinthModpack {
                project_id: project_id.clone(),
                version_id: version_id.clone(),
            })
        }
        _ if description.source_filename.is_some() => {
            Some(InstanceLink::ImportedModpack {
                project_id: None,
                version_id: None,
                name: Some(backup_name.to_string()),
                version_number: pack_version_id.map(ToString::to_string),
                filename: description.source_filename.clone(),
            })
        }
        _ => None,
    };
    let source_kind = match &link {
        Some(InstanceLink::ModrinthModpack { .. }) => {
            Some(ContentSourceKind::ModrinthModpack)
        }
        Some(InstanceLink::ImportedModpack { .. }) => {
            Some(ContentSourceKind::ImportedModpack)
        }
        _ => None,
    };
    crate::api::instance::edit(
        &instance_id,
        EditInstance {
            install_stage: Some(InstanceInstallStage::PackInstalling),
            name: Some(
                description
                    .override_title
                    .clone()
                    .unwrap_or_else(|| backup_name.to_string()),
            ),
            icon_path: description
                .icon
                .as_ref()
                .map(|icon| Some(icon.to_string_lossy().to_string())),
            link,
            content_set_patch: Some(AppliedContentSetPatch {
                source_kind,
                game_version: Some(game_version.clone()),
                protocol_version: Some(None),
                loader: Some(mod_loader),
                loader_version: Some(loader_version.clone().map(|x| x.id)),
            }),
            ..EditInstance::default()
        },
    )
    .await?;
    Ok(())
}