// LocalASRModelCatalog.swift
// OSGKeyboard · Shared
//
// Bundled catalog of downloadable / manual local ASR models and Sherpa runtimes.

import Foundation

public enum LocalASRModelBackend: String, Codable, Sendable, Equatable {
    case mlx
    case sherpaQwen3
    case sherpaSenseVoice
    case sherpaParaformer
    case appleSpeech
}

public enum LocalASRInstallKind: String, Codable, Sendable, Equatable {
    case manual
    case archive
    /// Multi-file install from a remote repository (ModelScope / HuggingFace file API).
    case repository
    case runtime
}

public struct LocalASRDownloadFile: Codable, Sendable, Equatable {
    public let remotePath: String
    public let localPath: String
    public let sizeBytes: Int?
}

public struct LocalASRDownloadSource: Codable, Sendable, Equatable {
    public let type: String
    public let priority: Int
    /// Full URL for a single archive download.
    public let url: String
    /// Base URL template for repository installs; must contain `{path}`.
    public let baseURL: String?
    public let files: [LocalASRDownloadFile]?

    public var isRepository: Bool {
        guard let files, !files.isEmpty else { return false }
        return baseURL?.contains("{path}") == true
    }

    public var isArchive: Bool {
        !url.isEmpty && !isRepository
    }
}

public struct LocalASRModelLayout: Codable, Sendable, Equatable {
    public var convFrontend: String?
    public var encoder: String?
    public var decoder: String?
    public var tokenizer: String?
    public var senseVoiceModel: String?
    public var paraformerModel: String?
    public var mlxConfig: String?
    public var mlxWeights: String?
    public var tokens: String?
}

public struct LocalASRRuntimeDefinition: Codable, Sendable, Equatable, Identifiable {
    public let id: String
    public let displayName: String
    public let installRelativePath: String
    public let binaryCandidates: [String]
    public let archiveFileName: String
    public let sizeBytes: Int
    public let platform: String
    public let sources: [LocalASRDownloadSource]
}

public struct LocalASRModelDefinition: Codable, Sendable, Equatable, Identifiable {
    public let id: String
    public let displayName: String
    public let backend: LocalASRModelBackend
    public let sizeBytes: Int
    public let recommendedLocales: [String]
    public let supportsHotwords: Bool
    public let hotwordMode: LocalASRHotwordMode
    /// Optional localization key for a short quality/speed badge
    /// (e.g. `mac.localASR.badge.fastest`).
    public let badgeKey: String?
    public let installKind: LocalASRInstallKind
    public let installRelativePath: String?
    public let archiveBaseName: String?
    public let layout: LocalASRModelLayout?
    public let requiredRelativeFiles: [String]?
    public let runtimePlatform: String?
    public let sources: [LocalASRDownloadSource]?
}

public struct LocalASRCatalogDocument: Codable, Sendable, Equatable {
    public let schemaVersion: Int
    public let defaultModelId: String
    public let runtimes: [LocalASRRuntimeDefinition]
    public let models: [LocalASRModelDefinition]
}

public enum LocalASRModelCatalog {

    public static func loadBundled() throws -> LocalASRCatalogDocument {
        let url =
            Bundle.main.url(forResource: "local-asr-catalog", withExtension: "json")
            ?? Bundle(for: LocalASRCatalogBundleToken.self)
            .url(forResource: "local-asr-catalog", withExtension: "json")
        guard let url else {
            throw LocalASRModelCatalogError.missingBundledCatalog
        }
        let data = try Data(contentsOf: url)
        return try JSONDecoder().decode(LocalASRCatalogDocument.self, from: data)
    }

    public static func model(_ id: String, in catalog: LocalASRCatalogDocument) -> LocalASRModelDefinition? {
        catalog.models.first { $0.id == id }
    }

    public static func capabilities(for model: LocalASRModelDefinition) -> LocalASRCapabilities {
        switch model.backend {
        case .mlx:
            return .qwen3MLX
        case .sherpaQwen3:
            return .sherpaQwen3
        case .sherpaSenseVoice:
            return .sherpaSenseVoice
        case .sherpaParaformer:
            return .sherpaParaformer
        case .appleSpeech:
            return .appleSpeech
        }
    }

    #if os(macOS)
    public static func runtime(for platform: String, in catalog: LocalASRCatalogDocument) -> LocalASRRuntimeDefinition? {
        if platform == "macos-arm64" {
            return catalog.runtimes.first { $0.platform == "macos-arm64" }
        }
        if platform == "macos-x64" {
            return catalog.runtimes.first { $0.platform == "macos-x64" }
        }
        return catalog.runtimes.first
    }

    public static func currentRuntimePlatform() -> String {
        #if arch(arm64)
        return "macos-arm64"
        #else
        return "macos-x64"
        #endif
    }
    #endif
}

/// User-facing override for which mirror to try first when installing models.
public enum LocalASRDownloadSourcePreference: String, Codable, Sendable, CaseIterable {
    /// Pick automatically based on the system region (China-friendly default).
    case auto
    /// Force the HF mirror (`hf-mirror.com`) first — best for mainland China.
    case hfMirror
    /// Force the official Hugging Face endpoint first.
    case huggingface

    /// The catalog `type` string this preference pins to the front (nil for `.auto`).
    public var pinnedType: String? {
        switch self {
        case .auto: return nil
        case .hfMirror: return "hfmirror"
        case .huggingface: return "huggingface"
        }
    }
}

/// Region-aware ordering for local ASR model download mirrors.
public enum LocalASRDownloadSourceSorter {

    /// `true` when the system region is mainland China (`CN`).
    public static func isChinaMainland(region: Locale.Region? = Locale.current.region) -> Bool {
        region?.identifier == "CN"
    }

    /// Whether to try the China-friendly mirror (`hf-mirror.com`) first.
    ///
    /// Default is "yes unless the region is *definitely* overseas": an unknown
    /// region (common when a VPN/proxy masks locale) falls back to the mirror,
    /// which is reachable both inside and outside China, so mainland users work
    /// out of the box while overseas users only lose it when their region is set.
    public static func preferChinaMirror(region: Locale.Region? = Locale.current.region) -> Bool {
        guard let region else { return true }
        return region.identifier == "CN"
    }

    /// Lower rank = tried earlier.
    /// China-first: hf-mirror → HuggingFace → ModelScope → GitHub.
    /// Overseas:    HuggingFace → hf-mirror → GitHub → ModelScope.
    public static func typeRank(_ type: String, chinaFirst: Bool) -> Int {
        switch type.lowercased() {
        case "hfmirror", "hf-mirror":
            return chinaFirst ? 0 : 1
        case "huggingface":
            return chinaFirst ? 1 : 0
        case "modelscope":
            return chinaFirst ? 2 : 3
        case "github":
            return chinaFirst ? 3 : 2
        default:
            return 4
        }
    }

    public static func sorted(
        _ sources: [LocalASRDownloadSource],
        region: Locale.Region? = Locale.current.region,
        preferred: LocalASRDownloadSourcePreference = .auto
    ) -> [LocalASRDownloadSource] {
        let chinaFirst = preferChinaMirror(region: region)
        let pinned = preferred.pinnedType?.lowercased()
        func rank(_ source: LocalASRDownloadSource) -> (Int, Int) {
            if let pinned, source.type.lowercased() == pinned {
                return (-1, source.priority)
            }
            return (typeRank(source.type, chinaFirst: chinaFirst), source.priority)
        }
        return sources.sorted { rank($0) < rank($1) }
    }
}

public enum LocalASRModelCatalogError: Error, LocalizedError {
    case missingBundledCatalog
    case modelNotFound(String)

    public var errorDescription: String? {
        switch self {
        case .missingBundledCatalog:
            return "Missing bundled local ASR catalog."
        case .modelNotFound(let id):
            return "Local ASR model not found: \(id)"
        }
    }
}

private final class LocalASRCatalogBundleToken {}