feat: add github fetcher layer

internal/github/fetcher.go

@@ -0,0 +1,130 @@
+package github
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+// now the nice thing is that I don't NEED to define a model always,
+// go can be "loose" if you want it to be
+// THis is unlike the geodata package where I made a model and all...
+
+// Uses the user's public github events api, filters for push events and returns
+// an array of .patch commits
+// Eg https://api.github.com/users/xyz/events/public to
+// https://api.github.com/repos/USER/REPO/commits/HASH
+func getPushPatches(user string) ([]string, error) {
+	url := fmt.Sprintf("https://api.github.com/users/%s/events/public", user)
+
+	// another neat way is that you don't NEED a Client
+	// it's good to have it for production for doing timeouts etc though
+	// this uses the global shared default client
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("github api failed")
+	}
+
+	var apiResult []map[string]any
+	// do YOU know diff b/w Unmarshal and NewDecoder?
+	if err := json.NewDecoder(resp.Body).Decode(&apiResult); err != nil {
+		return nil, fmt.Errorf("failed to decode github response")
+	}
+
+	// in place filter
+	end := 0
+	for _, entry := range apiResult {
+		if entry["type"].(string) == "PushEvent" {
+			apiResult[end] = entry // THESE are NOT copies, do YOU know why?
+			end++
+		}
+	}
+
+	// build patch urls
+	// do YOU know the diff b/w make vs declaring it using var
+	var patches []string
+	for i := 0; i < end; i++ {
+		repoPrefix := apiResult[i]["repo"].(map[string]any)["url"].(string)
+		commitHash := apiResult[i]["payload"].(map[string]any)["head"].(string)
+
+		patchUrl := fmt.Sprintf("%s/commits/%s", repoPrefix, commitHash)
+		patches = append(patches, patchUrl)
+	}
+
+	return patches, nil
+}
+
+func getUniqueTzFromPatches(patchUrls []string) ([]string, error) {
+	var tzs []string
+
+	for _, patchUrl := range patchUrls {
+
+		req, err := http.NewRequest("GET", patchUrl, nil)
+		if err != nil {
+			return nil, fmt.Errorf("failed to build req")
+		}
+
+		// Refer: https://docs.github.com/en/rest/commits/commits?apiVersion=2022-11-28#get-a-commit
+		// this is how YOU do custom stuff
+		req.Header.Set("Accept", "application/vnd.github.patch")
+
+		// can potentially run for INIFINITY as no timeout
+		resp, err := http.DefaultClient.Do(req)
+
+		if err != nil {
+			return nil, fmt.Errorf("failed to get patch")
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode != 200 {
+			// the DOCS say that some larges ones may time out
+			// and they DID
+			continue
+		}
+		// ^ THis is ugly
+
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read dpatch body")
+		}
+
+		// the date is the 3rd line
+		lines := strings.Split(string(body), "\n")
+		dateLine := lines[2]
+
+		if !strings.HasPrefix(dateLine, "Date: ") {
+			// my invariant failed and the world is ending
+			panic("invariant of date on 3rd line failed")
+		}
+
+		// split by space and pick last
+		spaceSplits := strings.Split(dateLine, " ")
+		if len(spaceSplits) == 0 {
+			panic("invariant of dateline having spaces failed")
+		}
+		tz := spaceSplits[len(spaceSplits)-1]
+
+		tzs = append(tzs, tz)
+	}
+
+	// uniq it now
+	// go seems to be getting a little TOO verbose for my taste now
+	seen := make(map[string]int)
+	end := 0
+	for _, tz := range tzs {
+		// the first is the value which is 0 if missing, second is the exists
+		if _, exists := seen[tz]; !exists {
+			seen[tz] = 1
+			tzs[end] = tz
+			end++
+		}
+	}
+
+	return tzs[:end], nil
+}