1 files changed, 194 insertions, 0 deletions
diff --git a/src/SMAPI.Web/Framework/ModSiteManager.cs b/src/SMAPI.Web/Framework/ModSiteManager.cs
new file mode 100644
index 00000000..68b4c6ac
--- /dev/null
+++ b/src/SMAPI.Web/Framework/ModSiteManager.cs
@@ -0,0 +1,194 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using StardewModdingAPI.Toolkit;
+using StardewModdingAPI.Toolkit.Framework.UpdateData;
+using StardewModdingAPI.Web.Framework.Clients;
+
+namespace StardewModdingAPI.Web.Framework
+{
+    /// <summary>Handles fetching data from mod sites.</summary>
+    internal class ModSiteManager
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The mod sites which provide mod metadata.</summary>
+        private readonly IDictionary<ModSiteKey, IModSiteClient> ModSites;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="modSites">The mod sites which provide mod metadata.</param>
+        public ModSiteManager(IModSiteClient[] modSites)
+        {
+            this.ModSites = modSites.ToDictionary(p => p.SiteKey);
+        }
+
+        /// <summary>Get the mod info for an update key.</summary>
+        /// <param name="updateKey">The namespaced update key.</param>
+        public async Task<IModPage> GetModPageAsync(UpdateKey updateKey)
+        {
+            // get site
+            if (!this.ModSites.TryGetValue(updateKey.Site, out IModSiteClient client))
+                return new GenericModPage(updateKey.Site, updateKey.ID).SetError(RemoteModStatus.DoesNotExist, $"There's no mod site with key '{updateKey.Site}'. Expected one of [{string.Join(", ", this.ModSites.Keys)}].");
+
+            // fetch mod
+            IModPage mod;
+            try
+            {
+                mod = await client.GetModData(updateKey.ID);
+            }
+            catch (Exception ex)
+            {
+                mod = new GenericModPage(updateKey.Site, updateKey.ID).SetError(RemoteModStatus.TemporaryError, ex.ToString());
+            }
+
+            // handle errors
+            return mod ?? new GenericModPage(updateKey.Site, updateKey.ID).SetError(RemoteModStatus.DoesNotExist, $"Found no {updateKey.Site} mod with ID '{updateKey.ID}'.");
+        }
+
+        /// <summary>Parse version info for the given mod page info.</summary>
+        /// <param name="page">The mod page info.</param>
+        /// <param name="subkey">The optional update subkey to match in available files. (If no file names or descriptions contain the subkey, it'll be ignored.)</param>
+        /// <param name="mapRemoteVersions">Maps remote versions to a semantic version for update checks.</param>
+        /// <param name="allowNonStandardVersions">Whether to allow non-standard versions.</param>
+        public ModInfoModel GetPageVersions(IModPage page, string subkey, bool allowNonStandardVersions, IDictionary<string, string> mapRemoteVersions)
+        {
+            // get base model
+            ModInfoModel model = new ModInfoModel()
+                .SetBasicInfo(page.Name, page.Url)
+                .SetError(page.Status, page.Error);
+            if (page.Status != RemoteModStatus.Ok)
+                return model;
+
+            // fetch versions
+            bool hasVersions = this.TryGetLatestVersions(page, subkey, allowNonStandardVersions, mapRemoteVersions, out ISemanticVersion mainVersion, out ISemanticVersion previewVersion);
+            if (!hasVersions && subkey != null)
+                hasVersions = this.TryGetLatestVersions(page, null, allowNonStandardVersions, mapRemoteVersions, out mainVersion, out previewVersion);
+            if (!hasVersions)
+                return model.SetError(RemoteModStatus.InvalidData, $"The {page.Site} mod with ID '{page.Id}' has no valid versions.");
+
+            // return info
+            return model.SetVersions(mainVersion, previewVersion);
+        }
+
+        /// <summary>Get a semantic local version for update checks.</summary>
+        /// <param name="version">The version to parse.</param>
+        /// <param name="map">A map of version replacements.</param>
+        /// <param name="allowNonStandard">Whether to allow non-standard versions.</param>
+        public ISemanticVersion GetMappedVersion(string version, IDictionary<string, string> map, bool allowNonStandard)
+        {
+            // try mapped version
+            string rawNewVersion = this.GetRawMappedVersion(version, map, allowNonStandard);
+            if (SemanticVersion.TryParse(rawNewVersion, allowNonStandard, out ISemanticVersion parsedNew))
+                return parsedNew;
+
+            // return original version
+            return SemanticVersion.TryParse(version, allowNonStandard, out ISemanticVersion parsedOld)
+                ? parsedOld
+                : null;
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get the mod version numbers for the given mod.</summary>
+        /// <param name="mod">The mod to check.</param>
+        /// <param name="subkey">The optional update subkey to match in available files. (If no file names or descriptions contain the subkey, it'll be ignored.)</param>
+        /// <param name="allowNonStandardVersions">Whether to allow non-standard versions.</param>
+        /// <param name="mapRemoteVersions">Maps remote versions to a semantic version for update checks.</param>
+        /// <param name="main">The main mod version.</param>
+        /// <param name="preview">The latest prerelease version, if newer than <paramref name="main"/>.</param>
+        private bool TryGetLatestVersions(IModPage mod, string subkey, bool allowNonStandardVersions, IDictionary<string, string> mapRemoteVersions, out ISemanticVersion main, out ISemanticVersion preview)
+        {
+            main = null;
+            preview = null;
+
+            ISemanticVersion ParseVersion(string raw)
+            {
+                raw = this.NormalizeVersion(raw);
+                return this.GetMappedVersion(raw, mapRemoteVersions, allowNonStandardVersions);
+            }
+
+            if (mod != null)
+            {
+                // get mod version
+                if (subkey == null)
+                    main = ParseVersion(mod.Version);
+
+                // get file versions
+                foreach (IModDownload download in mod.Downloads)
+                {
+                    // check for subkey if specified
+                    if (subkey != null && download.Name?.Contains(subkey, StringComparison.OrdinalIgnoreCase) != true && download.Description?.Contains(subkey, StringComparison.OrdinalIgnoreCase) != true)
+                        continue;
+
+                    // parse version
+                    ISemanticVersion cur = ParseVersion(download.Version);
+                    if (cur == null)
+                        continue;
+
+                    // track highest versions
+                    if (main == null || cur.IsNewerThan(main))
+                        main = cur;
+                    if (cur.IsPrerelease() && (preview == null || cur.IsNewerThan(preview)))
+                        preview = cur;
+                }
+
+                if (preview != null && !preview.IsNewerThan(main))
+                    preview = null;
+            }
+
+            return main != null;
+        }
+
+        /// <summary>Get a semantic local version for update checks.</summary>
+        /// <param name="version">The version to map.</param>
+        /// <param name="map">A map of version replacements.</param>
+        /// <param name="allowNonStandard">Whether to allow non-standard versions.</param>
+        private string GetRawMappedVersion(string version, IDictionary<string, string> map, bool allowNonStandard)
+        {
+            if (version == null || map == null || !map.Any())
+                return version;
+
+            // match exact raw version
+            if (map.ContainsKey(version))
+                return map[version];
+
+            // match parsed version
+            if (SemanticVersion.TryParse(version, allowNonStandard, out ISemanticVersion parsed))
+            {
+                if (map.ContainsKey(parsed.ToString()))
+                    return map[parsed.ToString()];
+
+                foreach ((string fromRaw, string toRaw) in map)
+                {
+                    if (SemanticVersion.TryParse(fromRaw, allowNonStandard, out ISemanticVersion target) && parsed.Equals(target) && SemanticVersion.TryParse(toRaw, allowNonStandard, out ISemanticVersion newVersion))
+                        return newVersion.ToString();
+                }
+            }
+
+            return version;
+        }
+
+        /// <summary>Normalize a version string.</summary>
+        /// <param name="version">The version to normalize.</param>
+        private string NormalizeVersion(string version)
+        {
+            if (string.IsNullOrWhiteSpace(version))
+                return null;
+
+            version = version.Trim();
+            if (Regex.IsMatch(version, @"^v\d", RegexOptions.CultureInvariant | RegexOptions.IgnoreCase)) // common version prefix
+                version = version.Substring(1);
+
+            return version;
+        }
+    }
+}