package workflow

import (
	"errors"
	"maps"
)

type Job struct {
	RunsOn string   `yaml:"runs-on"`
	Steps  []Step   `yaml:"steps"`
	Needs  []string `yaml:"needs"`
	// Job name; this isn't guaranteed to be unique.
	Name string `yaml:"name"`
	// If truthy, job-level failure does not bubble up to the workflow.
	ContinueOnError bool              `yaml:"continue-on-error"`
	Env             map[string]string `yaml:"env"`
	Defaults        struct {
		Run struct {
			WorkingDirectory string `yaml:"working-directory"`
			Shell            string `yaml:"shell"`
		} `yaml:"run"`
	} `yaml:"defaults"`
}

func (j Job) Walk(handler func(node interface{})) {
	handler(j)

	for _, step := range j.Steps {
		step.Walk(handler)
	}
}
func (j Job) Validate() []error {
	validationErrors := []error{}

	if j.RunsOn == "" {
		validationErrors = append(validationErrors, errors.New("Missing \"runs-on\" field on job."))
	}

	if len(j.Steps) == 0 {
		validationErrors = append(validationErrors, errors.New("Missing \"steps\" field on job."))
	}

	for _, step := range j.Steps {
		validationErrors = append(validationErrors, step.Validate()...)
	}

	return validationErrors
}

type Step struct {
	Run              string            `yaml:"run"`
	WorkingDirectory string            `yaml:"working-directory"`
	ContinueOnError  bool              `yaml:"continue-on-error"`
	Env              map[string]string `yaml:"env"`
	Shell            string            `yaml:"shell"`
	Use              string            `yaml:"use"`
}

func (s Step) Walk(handler func(node interface{})) {
	handler(s)
}

func (s Step) Validate() []error {
	validationErrors := []error{}

	if s.Run == "" && s.Use == "" {
		validationErrors = append(validationErrors, errors.New("Must have a \"run\" or \"step\" clause."))
	}

	return validationErrors
}

type Workflow struct {
	SourcePath string
	Jobs       map[string]Job    `yaml:"jobs"`
	Env        map[string]string `yaml:"env"`
}

func (w Workflow) Walk(handler func(node interface{})) {
	handler(w)

	for _, job := range w.Jobs {
		job.Walk(handler)
	}
}

// Returns the given workflow's job+step working directory inside the container
// that runs the job.
//
// Values considered, in order:
// - Step working-directory;
// - Job default run working-directory
func (w Workflow) GetWorkingDirectory(jobName string, stepIndex int) string {
	jobDefinition := w.Jobs[jobName]
	stepDefinition := jobDefinition.Steps[stepIndex]

	if stepDefinition.WorkingDirectory != "" {
		return stepDefinition.WorkingDirectory
	}

	if jobDefinition.Defaults.Run.WorkingDirectory != "" {
		return jobDefinition.Defaults.Run.WorkingDirectory
	}

	return "."
}

// Returns the merged map of environment variants defined by:
// - Workflow-level "env"
// - Job-level "env"
// - Step-level "env"
// The environment is merged in order, and name collisions overwrite
// previous values such that jobs can overwrite workflows, and steps, jobs.
func (w Workflow) GetEnv(jobName string, stepIndex int) map[string]string {
	finalEnv := map[string]string{}

	maps.Copy(finalEnv, w.Env)
	maps.Copy(finalEnv, w.Jobs[jobName].Env)
	maps.Copy(finalEnv, w.Jobs[jobName].Steps[stepIndex].Env)

	return finalEnv
}

// Returns the shell defined for the given job's step.
// Overriding values are considered in the order: step, job, global.
//
// If the shell is undefined in all cases, "bash" is used.
func (w Workflow) GetShell(jobName string, stepIndex int) string {
	var shell string

	if stepShell := w.Jobs[jobName].Steps[stepIndex].Shell; stepShell != "" {
		shell = stepShell
	} else if jobShell := w.Jobs[jobName].Defaults.Run.Shell; jobShell != "" {
		shell = jobShell
	}

	if shell == "" {
		return "bash"
	}

	return shell
}

func (w Workflow) Validate() []error {
	validationErrors := []error{}

	if len(w.Jobs) == 0 {
		validationErrors = append(validationErrors, errors.New("Missing \"jobs\" field on workflow."))
	}

	for _, job := range w.Jobs {
		validationErrors = append(validationErrors, job.Validate()...)
	}

	return validationErrors
}

// Creates a deterministic, ordered collection of jobs that respects
// the jobs's dependencies.
func (w Workflow) GetJobsAsGroups() [][]Job {
	dependenciesMap := map[string][]string{}

	for jobLabel, job := range w.Jobs {
		if len(job.Needs) == 0 {
			dependenciesMap[""] = append(dependenciesMap[""], jobLabel)
		}

		for _, need := range job.Needs {
			dependenciesMap[need] = append(dependenciesMap[need], jobLabel)
		}
	}

	levels := SplitFlatTreeIntoGroups(dependenciesMap)

	groups := [][]Job{}

	for _, jobLabels := range levels {
		jobs := []Job{}

		for _, jobLabel := range jobLabels {
			jobs = append(jobs, w.Jobs[jobLabel])
		}

		groups = append(groups, jobs)
	}

	return groups
}