1 files changed, 149 insertions, 0 deletions
diff --git a/internal/workflows/main.go b/internal/workflows/main.go
new file mode 100644
index 00000000..46f7e054
--- /dev/null
+++ b/internal/workflows/main.go
@@ -0,0 +1,149 @@
+//go:build workflows
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// KV represents a string to value pair.
+type KV[T any] struct {
+	K string
+	V T
+}
+
+// A Map represents an ordered set of key-value pairs.
+type Map[T any] []KV[T]
+
+// MarshalJSON encodes m as a key-value pair in JSON.
+func (m *Map[T]) MarshalJSON() ([]byte, error) {
+	if m == nil || len(*m) == 0 {
+		return []byte("{}"), nil
+	}
+
+	buf := bytes.NewBuffer(make([]byte, 0, len(*m)<<5))
+	buf.WriteByte('{')
+
+	last := len(*m) - 1
+	for i, pair := range *m {
+		p, err := json.Marshal(pair.K)
+		if err != nil {
+			return nil, fmt.Errorf("key %q: %w", pair.K, err)
+		}
+		buf.Write(p)
+		buf.WriteByte(':')
+
+		p, err = json.Marshal(pair.V)
+		if err != nil {
+			return nil, fmt.Errorf("value of key %q: %w", pair.K, err)
+		}
+		buf.Write(p)
+
+		if i < last {
+			buf.WriteByte(',')
+		}
+	}
+
+	buf.WriteByte('}')
+	return buf.Bytes(), nil
+}
+
+// A Step is a task ran as part of a [Job].
+type Step struct {
+	// A name for the step.
+	Name string `json:"name,omitempty"`
+	// Selects an action to run as part of a step in the job.
+	Uses string `json:"uses,omitempty"`
+	// A unique identifier for the step.
+	ID string `json:"id,omitempty"`
+	// Prevent a step from running unless a condition is met.
+	If string `json:"if,omitempty"`
+	// Runs command-line programs that do not exceed 21,000 characters using the
+	// operating system's shell.
+	Run string `json:"run,omitempty"`
+	// Key-value pairs of input parameters defined by the action.
+	With Map[any] `json:"with,omitempty"`
+}
+
+// A Job is an entry in a [Workflow] document.
+type Job struct {
+	// Set a name for the job.
+	Name string `json:"name,omitempty"`
+	// Identifies any jobs that must complete successfully before this job will
+	// run.
+	Needs []string `json:"needs,omitempty"`
+	// Define the type of machine to run the job on.
+	On string `json:"runs-on,omitempty"`
+	// A sequence of tasks.
+	Steps []Step `json:"steps,omitempty"`
+}
+
+// Workflow describes a workflow document.
+type Workflow struct {
+	// The name of the workflow.
+	Name string `json:"name,omitempty"`
+	// The name for workflow runs generated from the workflow.
+	RunName string `json:"run-name,omitempty"`
+	// Define which events can cause the workflow to run.
+	On any `json:"on"`
+
+	// Named jobs part of the workflow run.
+	Jobs Map[Job] `json:"jobs,omitempty"`
+}
+
+// workflowsDir is the relative pathname of the workflows directory.
+const workflowsDir = "../../.gitea/workflows"
+
+// writeFile writes the action to the .gitea directory.
+func (w *Workflow) writeFile(name string) error {
+	f, err := os.OpenFile(
+		filepath.Join(workflowsDir, name+".yml"),
+		os.O_CREATE|os.O_EXCL|os.O_WRONLY,
+		0444,
+	)
+	if err != nil {
+		return err
+	}
+
+	err = json.NewEncoder(f).Encode(w)
+	if closeErr := f.Close(); err == nil {
+		err = closeErr
+	}
+	return err
+}
+
+// removeOnce synchronises removal of stale workflow files.
+var removeOnce sync.Once
+
+// removeWorkflows removes existing workflow files once.
+func removeWorkflows() {
+	removeOnce.Do(func() {
+		if err := os.RemoveAll(workflowsDir); err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+		if err := os.Mkdir(workflowsDir, 0755); err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+	})
+}
+
+// mustWriteFile is like writeFile, but terminates the program if a non-nil
+// error is returned.
+func (w *Workflow) mustWriteFile(name string) (_ struct{}) {
+	removeWorkflows()
+
+	if err := w.writeFile(name); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	return
+}
+
+func main() {}