feat(gitlab-sim): ✨ first commit

internal/linter/needs.go

@@ -0,0 +1,123 @@
+package linter
+
+import (
+	"fmt"
+
+	"git.k3nny.fr/gitlab-sim/internal/model"
+)
+
+func checkNeeds(p *model.Pipeline) []Finding {
+	var findings []Finding
+
+	// Build a stage-index map for ordering checks.
+	stageIndex := make(map[string]int, len(p.Stages))
+	for i, s := range p.Stages {
+		stageIndex[s] = i
+	}
+
+	// needsGraph maps each job to the list of jobs it depends on.
+	// Used for cycle detection after individual checks.
+	needsGraph := make(map[string][]string)
+
+	for name, job := range p.Jobs {
+		if len(job.Needs) == 0 {
+			continue
+		}
+
+		neededNames := parseNeedJobNames(job.Needs)
+		needsGraph[name] = neededNames
+
+		jobStageIdx, jobHasStage := stageIndex[job.Stage]
+
+		for _, needed := range neededNames {
+			neededJob, exists := p.Jobs[needed]
+			if !exists {
+				findings = append(findings, Finding{
+					Severity: Error,
+					Job:      name,
+					Message:  fmt.Sprintf("needs unknown job %q", needed),
+				})
+				continue
+			}
+
+			// A job cannot need a job in a later stage.
+			if len(p.Stages) > 0 && jobHasStage && neededJob.Stage != "" {
+				neededStageIdx, neededHasStage := stageIndex[neededJob.Stage]
+				if neededHasStage && neededStageIdx > jobStageIdx {
+					findings = append(findings, Finding{
+						Severity: Error,
+						Job:      name,
+						Message: fmt.Sprintf(
+							"needs %q which is in a later stage (%q after %q)",
+							needed, neededJob.Stage, job.Stage,
+						),
+					})
+				}
+			}
+		}
+	}
+
+	findings = append(findings, detectNeedsCycles(needsGraph)...)
+	return findings
+}
+
+// parseNeedJobNames extracts job names from a needs: list.
+// Each element is either a plain string or a map with a "job" key.
+// Cross-pipeline needs (maps with a "pipeline" key) are skipped.
+func parseNeedJobNames(needs []any) []string {
+	var names []string
+	for _, n := range needs {
+		switch v := n.(type) {
+		case string:
+			names = append(names, v)
+		case map[string]any:
+			if _, crossPipeline := v["pipeline"]; crossPipeline {
+				continue
+			}
+			if job, ok := v["job"].(string); ok {
+				names = append(names, job)
+			}
+		}
+	}
+	return names
+}
+
+func detectNeedsCycles(graph map[string][]string) []Finding {
+	const (
+		unvisited = 0
+		visiting  = 1
+		visited   = 2
+	)
+
+	state := make(map[string]int, len(graph))
+	var findings []Finding
+	reported := make(map[string]bool)
+
+	var visit func(name string, path []string)
+	visit = func(name string, path []string) {
+		switch state[name] {
+		case visited:
+			return
+		case visiting:
+			if !reported[name] {
+				reported[name] = true
+				findings = append(findings, Finding{
+					Severity: Error,
+					Job:      name,
+					Message:  fmt.Sprintf("circular dependency in needs: %v → %s", path, name),
+				})
+			}
+			return
+		}
+		state[name] = visiting
+		for _, dep := range graph[name] {
+			visit(dep, append(path, name))
+		}
+		state[name] = visited
+	}
+
+	for name := range graph {
+		visit(name, nil)
+	}
+	return findings
+}